Solid-state laminate electrode assemblies and methods of making

ABSTRACT

Solid-state laminate electrode assemblies and various methods for making the solid-state laminate electrode assemblies involve a lithium metal layer reactively bonded to a lithium ion conducting sulfide glass layer. During manufacture, highly reactive surfaces of the lithium metal layer and the lithium ion conducting sulfide glass layer are maintained in its substantially unpassivated state until they have been reactively bonded.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 15/592,102, filed May 10, 2017, titled SOLID-STATE LAMINATE ELECTRODE ASSEMBLIES AND METHODS OF MAKING, which claims priority to U.S. Provisional Patent Application No. 62/334,327, filed May 10, 2016, titled PRISTINE LITHIUM METAL LAYERS AND ASSOCIATED COMPOSITIONS, STRUCTURES, COMPONENTS, BATTERY CELLS AND METHODS; 62/351,211, filed Jun. 16, 2016, titled PRISTINE LITHIUM METAL LAYERS AND ASSOCIATED COMPOSITIONS, STRUCTURES, COMPONENTS, BATTERY CELLS AND METHODS; 62/352,972, filed Jun. 21, 2016, titled PRISTINE LITHIUM METAL LAYERS AND ASSOCIATED COMPOSITIONS, STRUCTURES, COMPONENTS. BATTERY CELLS AND METHODS; 62/424,240, filed Nov. 18, 2016, titled PRISTINE LITHIUM METAL LAYERS AND ASSOCIATED COMPOSITIONS, STRUCTURES, COMPONENTS, BATTERY CELLS AND METHODS; 62/447,637, filed Jan. 18, 2017, titled PRISTINE LITHIUM METAL LAYERS AND ASSOCIATED COMPOSITIONS, STRUCTURES, COMPONENTS, BATTERY CELLS AND METHODS; 62/448,817, filed Jan. 20, 2017, titled STANDALONE LITHIUM METAL LAYER STRUCTURES, STANDALONE Li-ION CONDUCTIVE SOLID ELECTROLYTE LAYER STRUCTURES, AND ASSOCIATED COMPOSITIONS, LAMINATE STRUCTURES, COMPONENTS, BATTERY CELLS AND METHODS; the disclosures of which are incorporated by reference herein in their entirety and for all purposes.

STATEMENT OF GOVERNMENT SUPPORT

This invention was made with Government support under Award No.: DE-AR0000772 awarded by the Advanced Research Projects Agency—Energy (ARPA-E). U.S. Department of Energy. The Government has certain rights in this invention.

BACKGROUND

There is a continuing need for high performance battery cells, and their associated cell components, and particularly for high energy density rechargeable lithium metal batteries.

SUMMARY

The present disclosure describes solid-state laminate electrode assemblies and various methods for making the solid-state laminate electrode assemblies.

In one aspect the present disclosure provides methods for making a solid-state laminate electrode assembly.

In various embodiments the solid-state laminate electrode assembly comprises a lithium metal layer reactively bonded to a lithium ion conducting sulfide glass layer. Preferably, the reactive bond is sufficiently complete that it forms a continuous solid electrolyte interphase (SEI) at the boundary between the layers.

In various embodiments, to bring about a continuous SEI, the lithium metal layer should have a major surface, which, just prior to bonding (e.g., by laminating), is in a highly reactive state (i.e., it is substantially unpassivated). In various embodiments the method involves making a pristine lithium metal layer having a substantially unpassivated first major surface, and therefore highly reactive, and maintaining the highly reactive surface in its substantially unpassivated state until it has been reactively bonded with the sulfide glass layer.

In various embodiments the method comprises:

A method for making a solid-state laminate electrode assembly, the method comprising the steps of

-   -   i) providing a lithium metal laminate structure the laminate         comprising:         -   a. a lithium metal layer having a first major surface that             is substantially unpassivated; and         -   b. an inert protective material layer that removably covers             the lithium metal first major surface, the protective             material layer in direct contact with the lithium first             major surface;     -   ii) providing an inorganic solid electrolyte laminate structure,         the laminate comprising:         -   a. an inorganic lithium ion conducting sulfide glass layer             having a first major surface and an opposing second major             surface; and         -   b. an inert protective material layer that removably covers             the sulfide glass first major surface, the protective             material layer in direct contact with the sulfide glass;     -   iii) removing the inert protective material layer from the         lithium metal first major surface;     -   iv) removing the inert protective material layer from the         sulfide glass first major surface;     -   v) reactively bonding the sulfide glass layer with the lithium         metal layer via their first major surfaces; and     -   wherein the reactive bond is such that the interface between the         sulfide glass layer and the lithium metal is defined by a         continuous solid electrolyte interphase.

In various embodiments, the inert protective material layer on the sulfide glass first major surface is a liquid phase layer of a dry hydrocarbon liquid, and the inert protective material layer on the substantially unpassivated lithium metal first major surface is a liquid phase layer of a dry hydrocarbon liquid.

In various embodiments, the hydrocarbon liquid on the lithium metal surface is removed substantially immediately prior to the reactive bonding step, and optionally the hydrocarbon liquid on the sulfide glass is removed substantially immediately prior to reactively bonding step.

In various embodiments, the removal of the hydrocarbon liquid is accelerated by the application of one or more heat (conductive or convective), vacuum suction, blowing a jet of dry Ar or He, and blowing a jet of high vapor pressure protective liquid followed by vacuum suction.

In various embodiments, the step of cleaning the first major surface of the sulfide glass layer under an argon plasma, by ion etching; wherein the cleaning step is performed after the liquid phase layer of protective fluid has been removed.

In various embodiments, the step of treating the clean first major surface of the sulfide glass under a nitrogen containing plasma, wherein the treatment modifies the surface composition of the sulfide glass by introducing nitrogen into/onto the glass surface.

In various embodiments, the step of treating the clean sulfide glass first major surface to form a precursor film consisting of 1 to 5 monolayers of a halogen (e.g., iodine) or an interhalogen, or nitrogen onto the clean glass surface, wherein the monolayer(s) react with lithium on bonding to form a solid electrolyte interphase.

In various embodiments, the step of treating the clean sulfide glass first major surface to form a precursor film of nitrogen molecules on the glass surface.

In various embodiments, the solid electrolyte interphase comprises Li3N.

In various embodiments, a method of making a lithium metal layer having a substantially unpassivated first major surface, and preferably a pristine surface, includes extruding lithium metal directly into a liquid phase of protective fluid (e.g., super dry liquid hydrocarbon).

In various embodiments, a method of making a lithium metal layer having a substantially unpassivated first major surface, and preferably a pristine surface, includes extruding lithium metal and substantially immediately covering the freshly formed lithium metal surfaces with a liquid phase protective fluid.

In various embodiments, the extrusion comprises at least two extrusions performed by roll reduction, and the as-extruded lithium metal layers are substantially immediately covered in liquid phase protective fluid right after each roll reduction step, and maintained under liquid phase protective fluid throughout the process.

In various embodiments, the lithium metal layer is in the form of a long continuous roll, and the method further comprises the step of placing the lithium metal roll into a hermetic canister filled with liquid phase protective fluid, the lithium metal layer completely immersed within the protective fluid.

In various embodiments, the substantially unpassivated first major surface of the lithium metal layer has never been in direct touching contact with a gas phase atmosphere or vacuum.

In various embodiments, a lithium metal laminate structure is provided. The laminate includes:

-   -   i) a lithium metal layer having a first and second major         surface, wherein the first major surface is substantially         unpassivated; and     -   ii) a protective material layer that removably covers and         protects the lithium first major surface in direct contact.

In various embodiments, the substantially unpassivated lithium metal surface is stable.

In various embodiments, the protective material layer is an liquid phase hydrocarbon liquid, preferably super dry.

In various embodiments, an inorganic solid electrolyte laminate structure is provided. The laminate includes:

-   -   i) a lithium ion conducting sulfide glass layer having a first         and second major surface; and     -   ii) a protective material layer that removably covers and         protects the sulfide glass first major surface.

In various embodiments, the protective material layer is a liquid phase hydrocarbon liquid, preferably super dry.

In various embodiments, a method for storing a solid-state laminate electrode assembly is provided. The method includes making a solid-state laminate electrode assembly as described herein, and immersing the laminate electrode assembly into a bath of a liquid phase protective fluid (e.g., a super dry liquid hydrocarbon).

In various embodiments, a method for storing a lithium metal layer having a substantially unpassivated first major surface is provided. The method includes making the substantially unpassivated first major surface, and immersing the lithium metal layer into a bath of a liquid phase protective fluid (e.g., a super dry liquid hydrocarbon).

In various embodiments, a method for storing a sulfide glass layer having a clean first major surface is provided. The method includes cleaning the first major surface in an argon plasma, and immersing the sulfide glass layer into a bath of a liquid phase protective fluid (e.g., a super dry liquid hydrocarbon).

In various embodiments, a method for making a battery cell is provided. The method includes making a solid-state electrode assembly as described herein, and placing a positive electrode layer adjacent to the second surface of the sulfide glass layer.

These and other aspects of the present disclosure are described in further detail below, including with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process flow diagram for making a solid-state laminate electrode assembly in accordance with one embodiments of the present disclosure.

FIGS. 2A-D illustrate cross section depictions of standalone alkali metal laminate structures in accordance with various embodiments of the present disclosure.

FIGS. 2E-H illustrate cross section depictions of standalone inorganic solid electrolyte laminate structures in accordance with various embodiments of the present disclosure.

FIGS. 3A-E illustrate cross section and top down depictions of lithium metal layers and lithium metal surfaces.

FIGS. 4A-G illustrate apparatus' and method' for making a lithium metal layer having substantially unpassivated surfaces, in accordance with various embodiments of the present disclosure.

FIGS. 5A-B illustrate a lithium roll assembly cartridge according to one embodiment of the present disclosure.

FIG. 6A illustrates an apparatus and method for cleaning and treating an inorganic solid electrolyte layer, in accordance with an embodiment of the present disclosure.

FIG. 6B illustrates a cross section depiction of an inorganic solid electrolyte layer coated with a thin precursor film, in accordance with one embodiment of the present disclosure.

FIG. 7 illustrates a cross section depiction of a solid-state laminate electrode assembly in accordance with one embodiment of the present disclosure.

FIG. 8 illustrates an apparatus and method for making a solid-state laminate electrode assembly in accordance with one embodiment of the present disclosure.

FIG. 9 illustrates a roll assembly cartridge containing a solid-state laminate electrode assembly according to one embodiment of the present disclosure.

FIG. 10 illustrates a cross section depiction of a battery cell in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to specific embodiments of this disclosure. Examples of the specific embodiments are illustrated in the accompanying drawings. While this disclosure will be described in conjunction with these specific embodiments, it will be understood that it is not intended to limit this disclosure to such specific embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of this disclosure. In the following description, numerous specific details are set forth in order to provide a thorough understanding of this disclosure. This disclosure may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order to not unnecessarily obscure this disclosure.

INTRODUCTION

The present disclosure describes solid-state laminate electrode assemblies and various methods for making the solid-state laminate electrode assemblies.

In various embodiments the solid-state laminate electrode assembly comprises a lithium metal layer reactively bonded to a lithium ion conducting sulfide glass layer. Preferably, the reactive bond is sufficiently complete that it forms a continuous solid electrolyte interphase (SEI) at the boundary between the layers.

In various embodiments, to bring about a continuous SEI, the lithium metal layer should have a major surface, which, just prior to bonding (e.g., by laminating), is in a highly reactive state (i.e., it is substantially unpassivated). In various embodiments the method involves making a pristine lithium metal layer having a substantially unpassivated first major surface, and therefore highly reactive, and maintaining the highly reactive surface in its substantially unpassivated state until it has been reactively bonded with the sulfide glass layer.

In various embodiments, the present disclosure provides methods for making a solid-state laminate electrode assembly. Such a method includes:

-   -   ii) providing a lithium metal laminate structure the laminate         comprising:         -   a. a lithium metal layer having a first major surface that             is substantially unpassivated; and         -   b. an inert protective material layer that removably covers             the lithium metal first major surface, the protective             material layer in direct contact with the lithium first             major surface;     -   ii) providing an inorganic solid electrolyte laminate structure,         the laminate comprising:         -   c. an inorganic lithium ion conducting sulfide glass layer             having a first major surface and an opposing second major             surface; and         -   d. an inert protective material layer that removably covers             the sulfide glass first major surface, the protective             material layer in direct contact with the sulfide glass;     -   iii) removing the inert protective material layer from the         lithium metal first major surface;     -   iv) removing the inert protective material layer from the         sulfide glass first major surface;     -   v) reactively bonding the sulfide glass layer with the lithium         metal layer via their first major surfaces; and     -   wherein the reactive bond is such that the interface between the         sulfide glass layer and the lithium metal is defined by a         continuous solid electrolyte interphase.

In various embodiments the reactive bonding step is a lamination process performed in a chamber filled with a dry gas (e.g., dry argon). Typically the laminating step involves applying both heat and pressure.

In various embodiments the inert protective material layer removably covering one or both of the sulfide glass first major surface and the substantially unpassivated lithium metal surface is a liquid phase protective fluid.

In various embodiments the liquid phase protective fluid removably covering the lithium metal surface is removed just prior to the reactive bonding step (e.g., the period of time between removing the liquid phase protective fluid and reactive bonding is less than 10 seconds, and preferably less than 5 seconds, and even more preferably less than 2 seconds).

In various embodiments to ensure that the interface formed between the lithium metal layer and the lithium ion conducting sulfide glass is electrochemically operable or otherwise optimized, an SEI may be engineered by coating a first major surface of the sulfide glass with a thin precursor film that reacts with lithium metal during the bonding step to form a solid electrolyte interphase.

In some embodiments the sulfide glass surface may be treated under a nitrogen containing plasma to incorporate nitrogen into the surface of the glass, and then forming a lithium nitride.

In various embodiments the method further comprises the step of cleaning the first major surface of the sulfide glass under an argon plasma, by ion etching, this step performed after removing the inert protective material layer from of the sulfide glass but before reactive bonding.

In various embodiments the method further comprises the step of treating the clean sulfide glass first major surface to modify its surface composition. In various embodiments the surface composition is modified by placing the clean first major surface of the sulfide glass under a nitrogen containing plasma, wherein the treatment modifies the surface composition of the sulfide glass by introducing nitrogen into/onto the surface.

In various embodiments the method further comprises the step of coating the clean sulfide glass first major surface with a thin precursor film having a composition that will react in direct contact with lithium metal.

In various embodiments the thin precursor film is formed by condensing between 1 to 5 monolayers of a halogen (e.g., iodine) or interhalogen or nitrogen onto the clean sulfide glass surface; wherein the iodine monolayers leads to reactive wetting during the reactive bonding step.

In various embodiments the method further comprises coating the clean sulfide glass surface to form a precursor film that reacts with lithium during the reactive bonding step to form a solid electrolyte interphase between the lithium metal layer and sulfide glass layer.

In various embodiments the inert protective material layer removably covering one or both of the sulfide glass first major surface and the substantially unpassivated lithium metal surface is a liquid phase protective fluid.

In one aspect the present disclosure provides methods for making a pristine lithium metal layer having a substantially unpassivated first major surface, as defined herein below. In various embodiments the opposing second major surface of the pristine lithium metal layer is adhered to a current collector (e.g., a copper foil)

In various embodiments the pristine lithium metal layer is in the form of a long continuous roll of lithium that is immersed in liquid phase protective fluid for storage and/or downstream processing of battery cells (e.g., the pristine lithium metal layer at least 100 cm in length).

In various embodiments the method involves making the pristine lithium metal layer in a protective inert fluid, and maintaining the pristine lithium metal layer in protective fluid (e.g., protective liquid) to prevent directly exposing the surface to the ambient gaseous atmosphere (including dry argon of a glove box or dry Air of a dry room). In various embodiments the protective fluid is an inert liquid or the vapor of an inert liquid (i.e., protective vapor). In various embodiments the lithium metal layer is in the form of a long continuous ribbon (e.g., more than 50 cm in length).

In various embodiments the method for making the substantially unpassivated lithium metal surface includes an extrusion step that produces a fresh substantially unpassivated lithium first major surface inside or surrounded by protective fluid (e.g., a protective and super dry liquid hydrocarbon). By use of the term super dry it is meant that the amount of moisture in the liquid hydrocarbon is not greater than 0.1 ppm. In various embodiments the pristine lithium metal layer and its substantially unpassivated surface is extruded directly into liquid phase protective fluid (i.e., protective liquid), and then optionally the method further includes winding the lithium metal layer into a long continuous roll while it is immersed in liquid phase protective fluid.

In various embodiments the extrusion step is die extrusion of lithium ingot directly into a super dry liquid hydrocarbon bath. In various embodiments the extrusion step is a roller extrusion wherein the lithium metal foil thickness is roll reduced in protective liquid, and in the process forms fresh lithium substantially unpassivated lithium metal surfaces, wherein the area of the fresh surfaces so formed is proportional to the reduction in thickness of the lithium layer. In various embodiments multiple roll reduction steps are performed (e.g., 2, 3, 4 or 5 or more) in order to produce the desired thickness and to perfect the substantially unpassivated surface (e.g., a pristine surface). In various embodiments, the stock foil used for the roll reduction process has been pre-passivated, to improve reproducibility of the starting surface condition. In a particular embodiment a lithium ingot is die extruded directly into protective fluid to form a pristine lithium metal layer, and then that layer is immediately roll reduced in protective fluid to the desired thickness, and throughout the process the substantially unpassivated lithium metal surface remains covered or immersed in liquid phase protective fluid. The pristine lithium metal as formed may then be wound into a long continuous roll of pristine lithium metal, the winding performed in protective fluid (e.g. the winding performed inside liquid phase protective fluid).

In various embodiments the substantially unpassivated lithium metal surfaces are stored in a canister of protective liquid, or they are formed and immediately transferred into the canister, without exposing the surfaces to the ambient gaseous environment.

In another aspect the present disclosure provides a standalone electrochemical material laminate structure for maintaining a major surface of a battery active material layer in a substantially unpassivated and/or substantially uncontaminated condition during handling, storage and/or battery cell fabrication.

In various embodiments the battery active material layer reacts with water and/or oxygen, and even under fairly dry ambient conditions, such as that of a dry air room or a dry argon filled glove box the battery material surfaces chemically degrade or passivate rather quickly. The laminate structures of the present disclosure protect the battery material surfaces by encapsulating them underneath an inert removable layer, which inhibits moisture and/or oxygen from reaching the surfaces.

Accordingly, the standalone electrochemical material laminate structures of the present disclosure are particularly useful for making, storing and transporting moisture sensitive battery active material layers, and for making downstream battery cells and laminate electrode assemblies from those material layers.

In accordance with the present disclosure, a standalone electrochemical material laminate structure may be composed of two or more continuous material layers, wherein at least one of the material layers (i.e., a first material layer) is a “battery active solid material” having a clean (i.e., substantially uncontaminated) and/or substantially unpassivated surface, and another material layer (i.e., a second material layer) is a “protective material” that is inert, not battery active, and removably covers, in direct contact, a first major surface of the battery active material.

When referring to a material as “battery active” it generally means that the material is active in an electrochemical sense and useful in a battery cell (i.e., it is either an electro-active material or an electrolyte material). As used herein, the term “battery active solid material layer” means either a solid alkali metal or an inorganic solid electrolyte having utility as a continuous solid layer in a battery cell (e.g., a lithium metal layer or a Li-ion conducting sulfide glass sheet, respectively).

In contrast to the battery active material layer, the protective material layer is inert and not battery active. By use of the term “inert” it means that the referenced inert material does not chemically react in contact with the battery active solid material on which it is intended to protect. And when referring to the protective material layer as “not battery active,” it is meant that the material layer is not useful in a battery cell, and is furthermore not intended for use in a battery cell, and not active in a battery/electrochemical sense (i.e., not an electroactive material or alkali metal ion conductor).

In accordance with the present disclosure the protective material layer: i) provides an encapsulating barrier against direct touching exposure between the first major surface of the battery active material layer and the ambient gaseous atmosphere or contaminants in a vacuum chamber about the layer; ii) is inert in direct contact with the first major surface; and iii) is readily removed without physically damaging the surface. To achieve these objectives, in various embodiments the protective material layer is an inert liquid (e.g., a super dry hydrocarbon liquid) that encapsulates the surface on which it is applied, and may be evaporatively removed in the absence of solid to solid touching contact

In a first embodiment, the battery active material layer is an electroactive alkali metal layer having a substantially unpassivated first major surface (e.g., a pristine lithium metal layer), and in such embodiments the standalone electrochemical material laminate structure is generally referred to herein as a standalone alkali metal laminate structure; e.g., a standalone lithium metal laminate structure.

In a second embodiment, the battery active material layer is an inorganic solid electrolyte layer having a substantially uncontaminated first major surface (e.g., a lithium ion conducting sulfide glass sheet), and in such embodiments the standalone electrochemical material laminate structure is generally referred to herein as a standalone solid electrolyte laminate structure; e.g., a standalone sulfide glass laminate structure.

By use of the term “standalone” when referring to an electrochemical material laminate structure, such as a standalone alkali metal laminate structure or a standalone solid electrolyte laminate structure, it is meant to emphasis that the battery active material layer in the standalone laminate is a discrete battery active material layer that has not yet been combined or coupled with a second battery active material layer, or yet been placed in a battery cell.

In another aspect the present disclosure provides methods for making lithium metal layers having substantially unpassivated surfaces and preventing passivation by encapsulating them with inert liquid. In various embodiments the methods include making a lithium metal foil having substantially unpassivated surfaces by die extruding a lithium ingot into a bath of super dry liquid hydrocarbons. In various embodiments the as made substantially unpassivated lithium metal foil may be further reduced in thickness by roller reduction and applying hydrocarbon liquid onto the freshly formed surfaces to ensure that they remain substantially unpassivated. In various embodiments a pre-passivated lithium metal layer of thickness (t) may be roller reduced in a roller mill using multiple roll reduction steps while at all times maintaining liquid hydrocarbon on the freshly formed lithium metal layer surfaces. By using pre-passivated lithium metal (e.g., passivated by exposure to CO₂), reproducibility is improved because the initial surface condition of the lithium is itself reproducible, as opposed to using lithium metal that is passivated in a less or uncontrolled fashion. Moreover, the area of freshly formed lithium is proportional to the decrease in thickness of the layer.

In another aspect the present disclosure provides methods for making inorganic lithium ion conducting sulfide glass sheets having substantially uncontaminated surfaces, and for preventing hydrolysis of those surfaces by encapsulating them underneath an inert super dry hydrocarbon fluid (e.g., liquid). For instance, in various embodiments the inorganic sulfide glass sheets are cleaned by ion etching in an Ar plasma to etch away any contaminated surface(s), and then substantially immediately after the ion etching step, the cleaned sulfide glass sheet may be immersed in a liquid hydrocarbon bath, or the clean surface encapsulated by a protective liquid layer, as described above. In various embodiments, the surface composition of the sulfide glass may be modified during or immediately after cleaning by using an argon/nitrogen plasma mixture for incorporating nitrogen into the surface of the sulfide glass sheet, or the surfaces may be treated sequentially, using a first ion etch in argon plasma, followed by a second treatment in a nitrogen containing plasma (e.g., pure nitrogen or an argon/nitrogen mixture).

In yet another aspect the present disclosure provides methods of making a strongly adhered fully solid-state inorganic laminate electrode assembly having a substantially contaminate free inorganic interface. In various embodiments the method includes providing a first battery active material as a component of a lithium metal laminate structure (e.g., a lithium metal layer having a first major surface which is substantially unpassivated and protected by an inert hydrocarbon liquid layer); providing a second battery active material layer as a component of an inorganic solid electrolyte laminate structure (e.g., a lithium ion conducting sulfide glass sheet having a clean first major surface that is devoid of hydrolysis reaction products and protected by an inert hydrocarbon liquid layer); removing the inert hydrocarbon liquid layers; and then, substantially immediately thereafter, reactively bonding the substantially unpassivated lithium metal surface to the clean inorganic sulfide glass surface, to form a strongly adhered laminate having a clean inorganic interface with a low area resistance (preferably, less than 50 Ω-cm²). Preferably the peel strength of the laminate electrode assembly is greater than the tensile strength of its lithium metal layer, such that any attempt to peel off the lithium from the laminate results in the lithium tearing prior to peeling.

In various embodiments, an improved laminate interface is formed by laminating the fluid protected lithium metal surface to a solid electrolyte sheet using techniques whereby the fluid is removed substantially immediately prior to, or during, the laminating step, as the solid electrolyte comes into direct contact with the fluid and the lithium metal layer. In various embodiments, the laminating step effects a three phase boundary of lithium metal layer, solid electrolyte, and protective fluid, and causes the fluid to be removed from the surface substantially instantaneously as the solid electrolyte layer reactively adheres to the pristine lithium metal layer surface.

In another aspect, the present disclosure relates to methods and reagents to form a thin, dense and lithium ion conductive layer between a lithium metal layer and an inorganic solid electrolyte layer (e.g., a lithium ion conducting sulfide glass). The layer is sometimes referred to herein as a solid electrolyte interphase (SEI) as it is formed by reacting a first major surface of the lithium metal layer with a coating on the glass surface that allows for the glass electrolyte to be optimized for high ionic conductivity and processability, regardless of its chemical compatibility with lithium metal.

In another aspect the present disclosure provides methods of making battery cells by combining the fully solid-state inorganic laminate electrode assembly of the present disclosure with a positive electrode (e.g., a lithium ion intercalating positive electrode).

A list of suitable hydrocarbons which may be used as protective fluid (e.g., inert liquid) in accordance with the various embodiments and aspects of the present disclosure is provided below, as well as their structural formulas and vapor pressure (and/or boiling point) values. In various embodiments, the protective fluid is selected from a group of saturated hydrocarbons with the number of carbon atoms from 5 to 15. In one particular case, the protective fluid is isododecane. The protective fluids may be a combination of these various fluids. The fluids generally contain no dissolved or dispersed chemicals (e.g., salts, lubricants and/or greases) that would coat the surface of the lithium metal layer or solid electrolyte layer with a solid film or residue. Accordingly the protective fluid is devoid of any dissolved salts (e.g., lithium salts).

Suitable protective fluids are chemically inert to Li metal or Li alloys and contain less than 0.1 ppm of moisture, less than 1 ppm of moisture, less than 5 ppm of moisture, less than 10 ppm of moisture. In the case when a protective fluid is used in combination with a glass coating designed to form a solid electrolyte interphase (SEI) upon contact with Li, the protective fluid is chosen to be non-reactive with the glass coating.

Protective Fluids

Saturated Hydrocarbons (Alkanes) C_(n)H_(2n+2)

Straight-Chain Alkanes C₅-C₁₅

n-Pentane C₅H₁₂ BP=36° C., Vapor Pressure: 434 mmHg at 20° C.

n-Hexane C₆H₁₄ BP=69° C., Vapor Pressure: 121 mmHg at 20° C.

n-Heptane C₇H₁₆ BP=99° C., Vapor Pressure: 46 mmHg at 20° C.

n-Octane C₈H₁₈ BP=125° C., Vapor Pressure: 11 mmHg at 20° C.

n-Nonane C₉H₂₀ BP=151° C., Vapor Pressure: 3.8 mmHg at 25° C.

n-Decane C₁₀H₂₂ BP=174° C., Vapor Pressure: 2.7 mmHg at 20° C.

n-Undecane C₁₁H₂₄ BP=196° C., Vapor Pressure: 0.4 mmHg at 25° C.

n-Dodecane C₁₂H₂₆ BP=216° C., Vapor Pressure: 0.14 mmHg at 25° C.

Branched-Chain Alkanes C₅-C₁₅ Isopentane C₅H₁₂ BP=28° C., Vapor Pressure: 577 mmHg at 20° C.

Isohexane C₆H₁₄ BP=61° C., Vapor Pressure: 172 mmHg at 20° C.

Isoheptane C₇H₁₆ BP=90° C., Vapor Pressure: 66 mmHg at 20° C.

Isooctane C₈H₁₈ BP=99° C., Vapor Pressure: 41 mmHg at 21° C.

Tetraethylmethane C₉H₂₀ BP=146° C., Vapor Pressure: 7.3 mmHg at 25° C.

Isodecane C₁₀H₂₂ BP=167° C., Vapor Pressure: 2.3 mmHg at 25° C.

3-Methyldecane C₁₁H₂₄ BP=188° C., Vapor Pressure: N/A

Isododecane C₁₂H₂₆ BP=180° C., Vapor Pressure: 0.301 mmHg at 20° C.

Cycloalkanes C₆-C₈ C_(n)H_(2n) Cyclohexane C₆H₁₂ BP=81° C., Vapor Pressure: 78 mmHg at 20° C.

Cycloheptane C₇H₁₄ BP=118° C., Vapor Pressure: 22 mmHg at 20° C.

Cyclooctane C₈H₁₆ BP=149° C., Vapor Pressure: 16 mmHg at 37.7° C.

Unsaturated Acyclic Hydrocarbons C_(n)H_(2(n−m−1)), n=Number of Carbon Atoms m=Number of Double Bonds Alkenes C₆-C₁₁, C_(n)H_(2n) 1-Hexene C₆H₁₂ BP=64° C., Vapor Pressure: 155 mmHg at 21° C.

1-Heptene C₇H₁₄ BP=94° C., Vapor Pressure: 101 mmHg at 37.7° C.

1-Octene C₈H₁₆ BP=122° C., Vapor Pressure: 36 mmHg at 37.7° C.

1-Nonene C₉H₁₈ BP=146° C., Vapor Pressure: 11 mmHg at 37.7° C.

1-Docene C₁₀H₂₀ BP=172° C., Vapor Pressure: 1.67 mmHg at 25° C.

1-Undecene C₁₁H₂₂ BP=192° C. Vapor Pressure: N/A

1-Dodecene C₁₁H₂₄ BP=214° C., Vapor Pressure: N/A

Alkadienes: C₆-C₁₂ C_(n)H_(2n−2) 1,5-Hexadiene C₆H₁₀ BP=60° C., Vapor Pressure: 367 mmHg at 37.7° C.

2,4-Hexadiene C₆H₁₀ BP=82° C., Vapor Pressure: N/A

1,6-Heptadiene C₇H₁₂ BP=90° C., Vapor Pressure: N/A 1,7-Octadiene C₈H₁₄ BP=118° C., Vapor Pressure: 19 mmHg at 25° C.

1,8-Nonadiene C₉H₁₆ BP=141° C., Vapor Pressure: 7 mmHg at 25° C.

1,9-Decadiene C₁₀H₁₈ BP=169° C., Vapor Pressure: 4 mmHg at 20° C.

1,10-Undecadiene C₁₁H₂₀ BP=187° C., Vapor Pressure: N/A

1,11-Dodecadiene C₁₂H₂₂ BP=207° C., Vapor Pressure: N/A

Unsaturated Cyclic Hydrocarbons C_(n)H_(2(n−m)), n=Number of Carbon Atoms m=Number of Double Bonds Cycloalkenes C₆-C₈, C_(n)H_(2n−2) Cyclohexene C₆H₁₀ BP=83° C., Vapor Pressure: 160 mmHg at 20° C.

Cycloheptene C₇H₁₂ BP=113° C., Vapor Pressure: 22 mmHg at 20° C.

Cyclooctene C₈H₁₄ BP=145° C., Vapor Pressure: N/A

Cycloalkadienes C₆-C₈, C_(n)H_(2n−4) 1,3-Cyclohexadiene C₆H₈ BP=80° C., Vapor Pressure: 56 mmHg at 25° C.

1,4-Cyclohexadiene C₆H₈ BP=88° C., Vapor Pressure: N/A

1,3-Cycloheptadiene C₇H₁₂ BP=120° C., Vapor Pressure: N/A

1,3-Cyclooctadiene C₈H₁₄ BP=143° C., Vapor Pressure: 13.4 mmHg at 25° C.

Generally, the protective inert liquid layer is devoid of dissolved and/or dispersed chemicals (e.g., salts, lubricants and/or greases) that would coat the surface of the battery active material layer with a solid film or leave behind a sticky residue. Accordingly, the protective inert liquid layer is generally devoid of dissolved salts (e.g., lithium salts, or more generally alkali metal salts).

In order to be inert in direct contact with the battery active material layer, the liquid hydrocarbon(s) should have a very low concentration of moisture. Preferably the concentration of moisture in the inert liquid hydrocarbon layer is less than 10 ppm of water, more preferably less than 5 ppm of water, even more preferably less than 1 ppm of water, and yet even more preferably less than 0.1 ppm of water (i.e., super dry). In various embodiments the inert liquid is actively dried in the presence of sacrificial alkali metal surfaces (e.g., pieces/chips of lithium or sodium metal) that getter oxygen, water and nitrogen impurities. Moreover, the liquid hydrocarbons may be passed through a drying a chamber in order to maintain very low moisture levels. The drying chamber may contain drying agents and oxygen getters. Examples of drying agents for liquid hydrocarbons include molecular sieves (3A, 4A, or 5A depending on the hydrocarbon type), magnesium oxide, zinc chloride, calcium sulfate, calcium chloride, calcium hydride, and alumina (neutral or basic). In various embodiments, the cumulative area of the sacrificial alkali metal surfaces in direct contact with the inert liquid is greater than the first major surface of the battery active material layer on which the inert liquid covers in direct contact, for instance when the battery active material layer is disposed in a protective liquid bath, as described in more detail herein below.

Depicted Embodiments

In one aspect the present disclosure provides methods for making a solid-state laminate electrode assembly. In various embodiments, the solid-state laminate electrode assembly is a lithium metal layer reactively bonded with a lithium ion conducting sulfide glass layer.

With reference to FIG. 1 there is illustrated process flow diagram 5 for making a solid-state laminate electrode assembly in accordance with various embodiments of the present disclosure.

The process includes initial steps 10 and 20, for making or providing a first and a second standalone electrochemical material laminate structure, respectively. Notably, first and second electrochemical material laminate structures are not the same.

As used herein, the term electrochemical material laminate structure means a laminate of two or more continuous material layers, wherein at least one of the material layers (i.e., a first material layer) is a“battery active solid material layer” having a clean (i.e., substantially uncontaminated) and/or substantially unpassivated first major surface, and another material layer (i.e., a second material layer) is a “protective material layer” that is inert, not battery active, and removably covers, in direct intimate contact, the first major surface of the battery active material layer. In various embodiments the protective material layer is a liquid phase layer of a protective fluid, such as a super dry hydrocarbon liquid that is spread out evenly over the first major surface of the battery active material layer.

Generally, the battery active material layer is highly reactive with water and/or oxygen, and its surfaces chemically degrade or passivate rather quickly, even under dry or vacuum conditions, including that of a dry air room suited for handling lithium metal (e.g., having a dew point between −20 to −40° C.) or a dry argon filled glove box (e.g., having a low moisture and oxygen content of between 1 to 5 ppm). Accordingly, the electrochemical laminate structure is used to shield a battery active material layer against adverse reactions with the environment in which the battery active material layer is made, processed and/or stored. And by the term “solid battery active material layer” it is meant either a solid alkali metal layer (e.g., typically embodied herein as a lithium metal layer) or an inorganic solid electrolyte layer (e.g., typically embodied herein as a lithium ion conducting sulfide glass). When the battery active material layer is a lithium metal layer, the laminate structure is referred to generally as an alkali metal laminate structure (or more specifically in this case as a lithium metal laminate structure), and when the battery active material layer is an inorganic lithium ion conducting sulfide glass, the laminate structure is referred generally as a solid electrolyte laminate structure (or more specifically in this case as a sulfide glass laminate structure). Furthermore, by use of the term “standalone” when referring to an electrochemical material laminate structure, such as a standalone alkali metal laminate structure or a standalone solid electrolyte laminate structure, it is meant to emphasis that the battery active material layer in the standalone laminate is a discrete battery active material layer that has not yet been combined or coupled with a second battery active material layer, or yet been placed in a battery cell. For instance, when standalone lithium laminate structures are absent of an electrolyte and standalone sulfide glass solid electrolyte laminate structures are absent of battery electroactive materials.

Continuing with reference to FIG. 1 the first electrochemical material laminate structure, which is provided or made in process step 10 is a standalone lithium metal laminate structure, and the second electrochemical material laminate structure, which is provided in process step 20, is a standalone sulfide glass laminate structure. Once the laminate structures are provided (or made), the protective material layer on their respective first major surfaces is removed during process steps 12 and 22, and done without physically damaging the surfaces. As mentioned above, in various embodiments the protective material layer is an inert liquid phase layer of a super dry liquid hydrocarbon. Moreover, the liquid hydrocarbon employed herein as a protective material layer is selected, in part, based on its ability to remain on the surface of the lithium metal or sulfide glass layer until such time that it is to be controllably removed, rather than evaporating off by happenstance. Processes for accelerating and controllably removing the protective liquid layer from the battery active material layer can be performed in a chamber designed for that purpose. Such processes include one or more of heating, vacuum suction, blowing a jet of dry inert gas, blowing a jet of high vapor pressure protective fluid followed by vacuum suction, as well as rinsing the surfaces with protective fluids having progressively higher vapor pressures.

Once the protective material layer has been removed, it is important to minimize any exposure to gaseous or vacuum environments in order to maintain the respective battery active material layer surfaces clean and unpassivated. Accordingly, in some embodiments the chamber or conduit through which the battery active material layers are translated may be filled with vapor phase protective fluid right up until the layers are combined for lamination, according to process step 30, wherein the layers are reactively bonded to each other.

In various embodiments, once the liquid phase layer of protective fluid has been removed from the surface of the sulfide glass, the glass first major surface may be processed and/or treated prior to laminating with lithium metal in order to engineer a solid electrolyte interphase (SEI) with improved electrochemical properties, or when the sulfide glass is not chemically compatible with lithium metal. As described in more detail herein below, the sulfide glass may undergo a cleaning process 24A, exemplified by an ion etch treatment under an Ar plasma followed by a surface treating process 24B, wherein the cleaned glass surface may be coated with a thin lithium metal reactive precursor film or treated to modify the surface composition of the glass (e.g., by placing the glass first major surface under a nitrogen containing plasma).

The material laminate structures, methods and processes briefly described above with reference to process flow diagram in FIG. 1 are now described in more detail herein below, beginning with a description of the various architectures embodied for the standalone material laminate structures, followed by methods for making lithium metal layers having substantially unpassivated surfaces, as well as methods for treating the sulfide glass to an engineered solid electrolyte interphase.

Standalone Electrochemical Material Laminate Structure

In one aspect the present disclosure provides a standalone electrochemical material laminate structure for maintaining a major surface of a battery active material layer in a substantially unpassivated and/or substantially uncontaminated condition during storage and/or battery cell component fabrication (e.g., fabrication of a fully solid-state laminate electrode assembly).

In accordance with the present disclosure, the standalone electrochemical material laminate structure is composed of two or more continuous material layers, wherein at least one of the material layers (i.e., a first material layer) is a “battery active solid material layer” having a clean (i.e., substantially uncontaminated) and/or substantially unpassivated first major surface, and another material layer (i.e., a second material layer) is a “protective material layer” that is inert, not battery active, and removably covers, in direct contact, the first major surface of the battery active material layer.

In various embodiments the battery active material layer is highly reactive with water and/or oxygen, and its surfaces will chemically degrade or passivate rather quickly, even under fairly dry conditions of a dry Air room (e.g., having a dew point of −20° C.) or a dry argon filled glove box (e.g., having a low moisture and oxygen content of between 1 to 5 ppm).

In accordance with the present disclosure the protective material layer: i) minimizes, and preferably prevents, direct touching exposure between the first major surface of the battery active material layer and the ambient gaseous atmosphere or vacuum environment about the layer (e.g., during handling, processing and/or storage); ii) is inert in direct contact with the first major surface; and iii) is readily removed without physically damaging the surface. Accordingly, in various embodiments the protective material layer is an inert liquid (e.g., a super dry hydrocarbon liquid) that encapsulates the surface on which it is applied, and may be evaporatively removed in the absence of solid to solid touching contact.

In a first inventive embodiment, the battery active material layer is an electroactive alkali metal layer having a substantially unpassivated first major surface (e.g., a pristine lithium metal layer), and in such embodiments the standalone electrochemical material laminate structure is generally referred to herein as a standalone alkali metal laminate structure; e.g., a standalone lithium metal laminate structure. Preferably, the first major surface is pristine.

In a second inventive embodiment, the battery active material layer is an inorganic solid electrolyte layer (e.g., a lithium ion conducting sulfide glass sheet), and in such embodiments the standalone electrochemical material laminate structure is generally referred to herein as a standalone solid electrolyte laminate structure; e.g., a standalone sulfide glass laminate structure. In various embodiments the sulfide glass layer has a first major surface that is clean (i.e., substantially uncontaminated).

The standalone electrochemical material laminate structure of the present disclosure can be constructed using a number of different architectures, some of which are described in more detail herein below

With reference to FIGS. 2A-D and FIGS. 2E-H there are illustrated cross sectional depictions of standalone electrochemical material laminate structures in accordance with various embodiments of the present disclosure. The main differences between the structures shown in FIGS. 2A-D and those shown FIGS. 2E-H are the battery active material layer. Specifically, in FIGS. 2A-D the battery active material layer is lithium metal, and the electrochemical material laminate structure is a lithium metal laminate structure. In FIGS. 2E-H the battery active material layer is a lithium ion conducting sulfide glass, and the electrochemical material laminate structure is an inorganic solid electrolyte laminate structure. The laminate structures may take on a variety of shared architectures and these architectures are now described with reference to a battery active material layer. Thereafter, details particular to the lithium metal layer and to the sulfide glass layer are provided.

With reference to FIG. 2A and FIG. 2E there are illustrated fully encapsulated electrochemical material laminate structures 100A/200E in accordance with various embodiments of the present disclosure. Structure 100A/200E is composed of: i) freestanding battery active material layer 101/201 having first and second major surfaces (101 i/201 i and 101 ii/201 ii) and lengthwise edge surfaces (101 iii/201 iii and 101 iv/201 iv); and ii) inert liquid layer 102/202 encapsulating the major surfaces and the lengthwise edge surfaces (e.g., a super dry liquid hydrocarbon layer). In various embodiments inert liquid layer 102/202 is a super dry hydrocarbon that fully wets out the first and second major opposing surfaces and lengthwise edge surfaces (101 i, 101 ii, 101 iii, and 101 iv as well as 201 i, 201 ii, 201 iii, and 201 iv).

With reference to FIG. 2B and FIG. 2F there is illustrated a substrate supported electrochemical material laminate structure in accordance with various embodiments of the present disclosure. Structure 100/200F is composed of battery active material layer 101/201 and material backing layer 103/203, which may be rigid or flexible. In various embodiments layer 103/203 is a substrate onto which the battery active material layer is formed, or it (the backing layer) may be applied to second major surface 101 ii/201 ii after layer 101/201 has already been formed. Inert liquid layer 102/202 encapsulates first major surface 101 i/201 i, and may additionally encapsulate its lengthwise edge surfaces, as shown. In various embodiments backing layer 103 extends beyond layer 101/201, and the inert liquid wets out the lengthwise edges, as shown. In various embodiments, backing layer 103/203 is electronically insulating, and used generally as a supporting layer 101/201 during handling, storage and processing (e.g., as an interleave to facilitate winding and unwinding). For example, when the battery active material layer is sulfide glass solid electrolyte layer 201, backing layer 103 may be an inert organic polymer (e.g., a polyethylene or polypropylene film). In other embodiments, when the battery active material layer is lithium metal layer 101, backing layer 103 (flexible or rigid) may be electronically conductive, and thereon serve as a current collector in a battery cell. For instance, backing layer 103 may be a metal foil or mesh (e.g., copper), or it (backing layer 103) may be a thin copper film deposited on a polymer support layer (e.g., a polyester film). When backing layer 103 is intended to serve as a current collector, standalone electrochemical material laminate structure 100B is sometimes referred to herein as having electrode architecture.

With reference to FIG. 2C and FIG. 2G there is illustrated standalone electrochemical material layer structure 100C/200G, which, in accordance with various embodiments of the present disclosure has, what is termed herein, a wet-decal architecture, and for this reason structure 100C/200G is sometimes referred to herein more simply as a wet-decal or decal (e.g., Li-decal 100C or sulfide glass decal 200G). Laminate structure 100C/200G includes solid material release layer 104/204 covering but not touching battery active material layer surface 101 i/201 i, and inert liquid layer 102/202 sandwiched therebetween, and encapsulating the surface on which it is applied (101 i/201 i).

Preferably, the inert liquid of layer 102/202 completely wets out surface 101 i/201 i as well as the surface of release layer 104/204, and this leads to the formation of a liquid bridge between the layers and an associated wet adhesive force that assists in maintaining the release layer on the battery active material during handling and processing. The degree of wettability may be determined by the contact angle (θ). Accordingly, in various embodiments one criterion that may be used for selecting the protective liquid is based, in part, on its ability to fully wet out the battery active material surface on which it is disposed. To effect wetting the contact angle that the liquid makes with the solid surface should be in the range of 0°≥θ<90°, and preferably θ is near 0° for complete wet out (ε.γ., θ=0°). Preferably the ability of the inert liquid to wet out both surface 101 i/201 i and layer 104/204 is sufficient to spread the inert liquid layer evenly and intimately over surface 101 i/201 i, to encapsulate it (the first major surfaces) and prevent the solid release layer from touching the battery active material. Preferably, inert liquid layer 102/202 is thin enough to bring about a tight liquid bridge that is capable of maintaining the solid release on the battery active material during handling and processing.

Continuing with reference to FIG. 2C and FIG. 2G, in various embodiments the average thickness of protective liquid layer 102/202 is not greater than 50 um, or not greater than 25 μm, or not greater than 10 μm, or not greater than 5 μm, but sufficiently thick and uniform, nonetheless, to prevent contact between the release layer and surface 101 i (e.g., 50 μm>t>5 μm; or 5 μm>t>100 nm). In various embodiments, inert liquid layer 102/202 has an average thickness in the range of 1 μm>t>100 nm; or in the range of 5 μm>t>1 μm; or in the range of 50 μm>t>5 μm. However, the present disclosure is not limited as such, and it is contemplated that structure 100C/200C may have pockets or isolated locations that are not covered by protective liquid, and in such embodiments, it is especially important that release layer 104/204 is inert in contact with the batter active material.

The wet decal architecture, as described above, has a number of advantages, including: i) protecting surface 101 i/102 i against physical damage during handling; ii) enhancing the utility and/or the ability to use medium to high vapor pressure inert liquids by lessening their effective evaporation rate; iii) improving protection against degradation of surface 101 i/201 i against impurity molecules from the ambient atmosphere, as the release layer itself provides an additional barrier against contaminating molecules entering the protective liquid from the ambient atmosphere; iv) extending storage shelf life and service lifetimes due to the additional barrier properties and lower evaporation rate of the inert liquid layer; and finally v) the solid release layer may serve as an interleave for winding or stacking the laminate structures.

With reference to FIG. 2D and FIG. 2H, in various embodiments the wet-decal architecture is sealed along its lengthwise edges by seal 113/213, the seal providing an additional barrier against diffusion of impurity molecules from the ambient atmosphere seeping into the inert liquid layer and for minimizing evaporation of the inert liquid out from the laminate. When sealed, the lengthwise edges are preferably also covered in direct contact with inert liquid. Lengthwise edge seal 113/213 may be made by heat and pressure applied between release layer 104/204 and backing layer 103/203, which, in various wet-decal embodiments is simply a second release layer, similar or the same as layer 104/204. In embodiments wherein structure 100D/200H includes current collector layer 103, an additional sealable backing layer may be placed behind the current collecting layer, for sealing the lengthwise edges. During downstream processing, when the release layer needs to be removed, the edge seal may be broken by slicing with a sharp edge.

In various embodiments the laminate thickness, as measured from the second major surface of the battery active material layer 101 ii/201 ii to the top surface of inert liquid layer 102/202 is no greater than 1 mm thick, and more typically no greater than 500 um thick. For instance, in various embodiments the laminate thickness (as defined above) is less than 500 um, and typically less than 200 um, and in some embodiments less than 100 um, or less than 50 um (e.g., between 5-100 um). The laminate thickness, as defined above, does not include the thickness of the solid release layer, or backing layer when present.

Liquid Phase Protective Fluid Layer

In accordance with the present disclosure one function of protective material layer 102/202 (e.g., inert liquid layer) is to removably cover and protect (e.g., encapsulate) at least the first major surface of the battery active material layer, and thereon provide a degree of protection against facile degradation caused by direct exposure of the lithium metal layer or sulfide glass layer to ambient gaseous atmospheres during handling, processing and/or storage. By use of the term “removably cover and protect” when describing the protective inert liquid layer it is meant that the layer: i) covers the first surface of the battery active material in a manner that sufficiently protects the surface against chemical attack; ii) remains on the first surface during handling and storage; and iii) can be controllably removed without damaging the battery active material layer. By use of the term “controllably remove” or “controllably removed” when referring to the protective material layer it is meant that the laminate structure is engineered to facilitate removal of the protective material layer in a controlled fashion, and is otherwise not easily removed (e.g., by happenstance, such as incidental evaporation during handling and processing of downstream components). Accordingly, the chemical make-up and physical properties of the protective material layer is properly selected to enable its controlled removal without damaging the battery active material layer, and the laminate structure engineered to ensure that the inert material layer stays intact as a protective layer for the desired time frame.

In various embodiments protective material layer 102/202 is an inert liquid that intimately covers and spans substantially the first major surface of the battery active material layer (i.e., it is a continuous inert liquid layer). Accordingly, in various embodiments the composition of the inert liquid is selected, in part, based on it having a lower surface energy than the battery active material layer surface, and therefore capable of wetting out the battery active first major surface, and, thus, intimately covering it in direct contact, the liquid flowing and spreading out evenly to span substantially the entire surface (i.e., encapsulate the surface); e.g., encapsulate the first major surface.

Preferably inert liquid layer 102/202 readily wets the first major surface of the battery active material layer. In various embodiments, the wetting angle (θ) that the inert liquid makes in contact with the battery active material layer is less than 90° (e.g., 0≥θ<90°), preferably less than 60°, more preferably less than 30°, even more preferably θ is less than 10°, and yet even more preferably about 0°. Accordingly, in various embodiments, the ability of the inert liquid layer to wet the battery active material layer surface is sufficient to encapsulate the one or more surfaces that it covers in direct contact.

Generally, the thickness of inert liquid layer 102/202 is less than 1 mm. In embodiments the thickness of the continuous inert liquid layer is in the range of 500 to 1000 um; or in the range of 200 to 500 um; or in the range of 100 to 200 um; or in the range of 50 to 100 um; or in the range of 20-50 um; or in the range of 10-20 um or in the range of 5-10 um; or in the range of 1-5 um; or, in some embodiments, it is contemplated that it may be less than 1 um.

In various embodiments, in order to retain inert liquid layer 102/202 on the surface of the battery active material layer during handling and processing, and controllably remove it (the inert liquid layer) without imparting damage or leaving behind a chemical residue, the inert liquid is selected based on a combination of its vapor pressure and boiling point.

In various embodiments, in order to mitigate uncontrolled evaporation of inert liquid layer 102/202, while facilitating its controlled removal, the inert liquid of the protective material layer (i.e., the inert liquid layer) is selected, in part, based on having a room temperature vapor pressure in the range of 0.1-10 mmHg (e.g., 0.1-1 mmHg), and/or based, in part, on having a boiling temperature in the range of 100-200° C.

In various embodiments, the inert liquid of protective material layer 102/202 is selected based on having a sufficiently low vapor pressure at room temperature (e.g., less than 10 mmHg, or less than 1 mmHg).

In various embodiments, the inert liquid of protective material layer 102/202 is selected based on having a sufficiently high boiling point temperature (e.g., greater than 100° C., or greater than 150° C. or greater than 200° C.).

In various embodiments the inert liquid of protective material layer 102/202 is selected based on having a room temperature vapor pressure that is less than 10 mmHg and a boiling point temperature greater than 100° C.

In various embodiments protective material layer 102/202 is composed of one or more inert hydrocarbon liquids (e.g., isododecane). Particularly suitable hydrocarbon liquids for use as a protective material layer are saturated hydrocarbons (e.g., having a number of carbon atoms per molecule ranging from 5 to 15).

In various embodiments the inert hydrocarbon liquid is a saturated hydrocarbon liquid.

In some embodiments the protective inert liquid saturated hydrocarbon is a straight chain alkane (typically having between 5 and 15 carbon atoms per molecule), such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane.

In some embodiments the protective inert liquid saturated hydrocarbon is a branched chain alkane (typically having 5 to 15 carbon atoms per molecules), such as isopentane, isohexane, isoheptane, isooctane, tetraethylmethane, isodecane, 3-methyldecane, isododecane.

In some embodiments the protective inert liquid saturated hydrocarbon is a cycloalkane, such as cyclohexane, and cycloheptane, cyclooctane.

In some embodiments the protective inert liquid hydrocarbon is an unsaturated acyclic hydrocarbon (e.g., C_(n)H_(2(n−m−1)) wherein n is the number of carbon atoms and m is the number of double bonds), such as alkenes (e.g., 1-hexane, 1-octane, 1-nonene, 1-docene, 1-undecene, 1-dodecene, or alkadienes (e.g., 1,5-hexadiene; 2,4-hexadiene; 1,6-heptadiene; 1,7-octadiene; 1,8-nonadiene; 1,9-decadiene; 1,10-undecadiene; and 1,11-dodecadiene.

In various embodiments the inert hydrocarbon liquid is an unsaturated hydrocarbon liquid.

In some embodiments the protective inert liquid is an unsaturated cyclic hydrocarbon (e.g., of the type C_(n)H_(2(n−m)) wherein n is the number of carbon atoms and m is the number of double bonds), such as cyclohexane, cycloheptane, and cyclooctene).

In some embodiments the protective inert liquid is an unsaturated cyclic hydrocarbon (e.g., one or more cycloalkadienes), such as 1,3-cyclohexadiene; 1,4-cyclohexadiene; 1,3-cycloheptadiene; and 1,3-cyclooctadiene).

Generally, protective inert liquid layer 102/202 is devoid of dissolved and/or dispersed chemicals (e.g., salts, lubricants and/or greases) that would coat the surface of the battery active material layer with a solid film or leave behind a sticky residue. Accordingly, the protective inert liquid layer is generally devoid of dissolved salts (e.g., lithium salts, or more generally alkali metal salts).

In order to be inert in direct contact with the battery active material layer, the liquid hydrocarbon(s), and, more generally, the protective inert liquid layer should have a very low concentration of moisture. Preferably the concentration of moisture in the inert liquid hydrocarbon layer is less than 10 ppm of water, more preferably less than 5 ppm of water, even more preferably less than 1 ppm of water, and yet even more preferably less than 0.1 ppm of water (i.e., super dry). In various embodiments the inert liquid is actively dried in the presence of sacrificial alkali metal surfaces (e.g., pieces/chips of lithium metal) that getter oxygen, water and nitrogen impurities. In various embodiments, the cumulative area of the sacrificial alkali metal surfaces in direct contact with the inert liquid is greater than the first major surface of the battery active material layer on which the inert liquid covers in direct contact, for instance, when the battery active material layer is disposed in a protective liquid bath, as described in more detail herein below.

Standalone Alkali Metal Laminate Structures

In accordance with the standalone electrochemical material laminate structure embodiments described with reference to FIGS. 2A-D, the laminate structures 100A-D are alkali metal laminate structures wherein battery active material layer 101 is an alkali metal layer having substantially unpassivated first major surface 101 i, and preferably surface 101 i is pristine.

In various embodiments alkali metal layer 101 is a dense alkali metal layer. In various embodiments it is a lithium metal layer or sodium metal layer. It is also contemplated that the alkali metal layer may be a lithium metal alloy or a sodium metal alloy, which may include one or more of the following alloying elements, including Ca, Mg, Sn, Ag, Zn, Bi, Al, Cd, Ga, In and Sb. In various embodiments alkali metal layer 101 is a lithium metal layer.

In various embodiments thickness of lithium metal layer 101 is typically no greater than 50 microns, and more typically no greater than 25 microns (e.g., 50 μm≥t>30 μm; or 30 μm≥t>20 μm; or 20 μm≥t>10 μm; or 10 μm≥t≥5 μm). In some embodiments lithium metal layer 101 is a thin film coating on a current collector having a scant amount of lithium, with thickness no greater than 5 um thick, and typically thinner, such as about 4 μm or about 3 μm or about 2 μm or about 1 μm, or less than 1 μm (e.g., 5 μm>t≥0.1 μm). For example, the thin film of lithium metal may be coated by evaporation onto a copper current collector in a vacuum chamber, and then prior to backfilling the chamber with a dry inert gas, such as argon or helium, the first major surface of the coated film is immersed in protective liquid or coated with a layer of inert protective liquid.

In accordance with the present disclosure, in various embodiments, lithium metal surface 101 i is substantially unpassivated and preferably pristine, as defined herein below. And even more preferably, lithium metal surface 101 i is 100% unpassivated. Preferably, lithium metal surface 101 i is 100% unpassivated and molecularly or atomically clean.

Continuing with reference to the lithium metal laminate structures described herein above with reference to FIGS. 2A-D, in various embodiments first major surface 101 i of lithium metal layer 101 is substantially unpassivated (or pristine), and is able to remain substantially unpassivated (or pristine) for a duration of at least 10 seconds, or at least 1 minute, or at least 5 minutes, or at least 10 minutes when it (the laminate structure) is disposed in a dry chamber having a water and oxygen content of about 1 to 10 ppm (e.g., about 5 ppm).

By use of the term “pristine surface” with reference to alkali metal layer 101 (e.g., a lithium metal layer), it is meant a substantially unpassivated lithium metal surface that is also sufficiently clean to i) facilitate complete reactive bonding to an opposing solid electrolyte layer, wherein the adherence created by the complete bond is sufficiently strong to prevent mechanical non-destructive release or delamination between the layers; and ii) effectuate a sufficiently uncontaminated interface (with the solid electrolyte layer) that is conductive to Li ions and does not result in a prohibitively large interface resistance (preferably no greater than 50 Ω-cm²) between the alkali metal layer (e.g., a lithium metal layer) and the solid electrolyte layer (e.g., a sulfide glass layer).

By “substantially unpassivated” when referring to an alkali metal layer surface (e.g., a lithium metal surface) it is meant that the surface is predominately defined by a continuous unpassivated and substantially unoxidized surface region that accounts for at least 70% of the area of the referenced lithium metal surface (e.g., first major surface 101 i). When referring to a lithium metal layer surface as pristine it is meant that the continuous unpassivated and substantially unoxidized surface region accounts for at least 90% of the area of the referenced lithium metal surface, and preferably at least 95%, and even more preferably the pristine surface is entirely unpassivated (i.e., 100% of the surface is unpassivated). In various embodiments, as described in more detail herein below, the substantially unpassivated or pristine surface may contain a certain amount of discrete passivated surface portions (i.e., passivated islands).

By “sufficiently clean” when referring to the pristine lithium metal surface, it is meant that the continuous unpassivated and substantially unoxidized surface region, as described above, is not poisoned by an unduly thick non-self-limiting surface-layer, which, if otherwise present would preclude complete reactive bonding and strong adherence to a reactive solid electrolyte layer (e.g., as defined with respect to peel strength), and would degrade electrochemical interface properties (e.g., as defined by interface resistance, and uneven plating and stripping reactions). Notwithstanding the preference to eliminate any poisoning of the pristine surface, a minimal non-self-limiting surface-layer covering the continuous unpassivated region may be acceptable, as described in more detail herein below.

Top down and cross sectional depictions of alkali metal layers (e.g., lithium metal layers) having pristine surfaces in accordance with various embodiments of the present disclosure are depicted in FIGS. 3A-D; and for comparison, passivated lithium metal layer 3E-101 is depicted in FIG. 3E.

Briefly, in FIG. 3A, lithium metal layer 3A-101 is shown having pristine surface 3A-101 i that is 100% unpassivated, and molecularly or atomically clean; in FIG. 3B, pristine surface 3B-101 i of lithium metal layer 3B-101 contains a certain amount of passivating islands 3B-160 dispersed on continuous unpassivated region 3B-165; in FIG. 3C, the pristine surface of lithium metal layer 3-101C is covered by minimal surface-layer 3C-181, which defines the surface of its unpassivated region, and has an average thickness that is preferably less than 10 nm; and in FIG. 3D pristine surface 3D-101 i includes passivating islands 23D-160 and minimal surface-layer 3D-181 which defines the surface of its unpassivated region. Prior to describing these embodiments in more detail, it is instructive, for the purpose of comparison, to first depict the make-up of a fully passivated lithium layer.

With reference to FIG. 3E, a depiction of fully passivated lithium metal layer 3E-101 which may be a lithium metal foil that was made by extrusion and/or roller reduction in a dry air, dry oxygen and/or dry CO₂ gaseous environment (e.g., dry air room), or it (layer 3E-101) may be an evaporated thin lithium film deposited on a current collector (not shown) under vacuum in a chamber, and then breaking the vacuum by bleeding a stream of dry air, dry oxygen and/or dry CO₂ (e.g., dry air) into the chamber. The exposure to dry air immediately upon making the lithium foil/film results in the formation of passivation film 3E-179, which is a dense substantially self-limiting film of lithium oxide, and it may be several hundred angstroms thick (e.g., about 500 A), or thicker, when formed in a dry room atmosphere (i.e., dry air). The exact stoichiometry of the passivating film is difficult to ascertain, and so is generally referred to as Li₂O_(x). Alternatively, if formed in the presence of dry CO₂ gas, the composition of the passivating film is primarily lithium carbonate. By use of the term substantially self-limiting it is meant that the passivating film, formed as such, is sufficiently dense and thick to effectively block further reactions and thereby mitigate subsequent film growth. For instance, lithium passivating film 3E-179, once completely formed, is chemically stable to exposure to dry room air unless subjected to an atmosphere having a prohibitively high concentration of a reactive impurity such as water, which is known to breakdown lithium passivating films overtime.

With reference to FIG. 3-A, pristine surface 3A-101 i of lithium metal layer 3A-101 is 100% unpassivated and substantially unoxidized, and absent of even a minimal surface-layer contaminant.

With reference to FIG. 3B, pristine surface 3B-101 i of alkali metal layer 3B-101 contains passivated islands 3B-160 dispersed throughout continuous unpassivated and substantially unoxidized surface region 3B-165. The cumulative area of the islands is less than 10% of the total area of the first major surface, and preferably the cumulative area is less than 5%, and even more preferably less than 1%. Preferably, the area size of the islands does not exceed 1 mm², and more preferably does not exceed 0.5 mm², and even more preferably does not exceed 0.1 mm². In certain embodiments the method of making alkali metal layer 3B-101 results in first major surface 3B-101 i that is characterized as predominately unpassivated (as opposed to pristine), wherein the area of continuous unpassivated region 3B-165 accounts for less than 90%, but at least 70%, of the area of first major surface 3B-101 i.

With reference to FIG. 3C, pristine surface 3C-101 i of alkali metal layer 3C-101 is defined, in part, by the presence of non-self-limiting minimal surface-layer 3C-181 composed of an ionically and/or covalently bonded compound which forms as a result of alkali metal atoms of the continuous unpassivated region oxidizing in contact with reactive impurity molecules derived from the external environment about the alkali metal layer structure, and especially oxygen, nitrogen and/or water impurities which may be present in the ambient gas or ambient vacuum of the external environment in which the alkali metal layer is formed, stored and/or handled, and/or as impurities in the protective liquid in which it (the pristine surface) is preserved. In various embodiments, minimal surface-layer 3C-181 is a compound product of the alkali metal atoms reacting with one or both of oxygen and water present as an impurity, and generally derived from the ambient gas of the external environment; for instance, surface-layer 3C-181, an alkali metal oxyhydroxide compound (e.g., lithium oxyhydroxide). Minimal surface-layer 3C-181 is not necessarily continuous as shown in FIG. 3C, and may be spread out as discrete sections over the continuous unpassivated region. When present, surface-layer 3C-181 is minimal and exceptionally thin, having an average thickness that is less than 200 Å, and more preferably less than 100 Å, and even more preferably less than 50 Å or less than 40 Å or less than 30 Å. Even more preferably, the pristine surface is characterized as molecularly clean, which is to mean that the average thickness of surface-layer 3C-181 is less than 25 Å, and even more preferably the pristine surface is atomically clean, with surface-layer 3C-181 181 having an average thickness of less than 10 Å.

With reference to FIG. 3D, lithium metal layer 3D-101 has pristine surface 3D-101 i which is similar to that shown in FIG. 3C in that the unpassivated surface region is defined by a minimal surface-layer 3D-181, similar to 3C-181 (as described above and shown in FIG. 3C), but also containing passivating islands 3D-160, similar to the passivating islands described above with reference to FIG. 3B.

Methods of Making Pristine Lithium Metal Layers and Lithium Metal Layers Having Substantially Unpassivated Surfaces.

As described above, the present disclosure provides methods and apparatus' for making lithium metal layers having substantially unpassivated and preferably pristine surfaces, and, in particular, for making lithium metal layers wherein at least one major surface is maintained in its pristine or substantially unpassivated condition under, or immersed in, a protective fluid (e.g., a protective liquid).

With reference to FIGS. 4A-D there are illustrated apparatus' 400A-D for the manufacture of lithium metal layer 101, having first and second major opposing surfaces 101 i/101 ii, wherein at least first surface 101 i is formed in direct contact with protective fluid 102 (e.g. super dry inert hydrocarbon liquid, vapor or combination thereof), and therewith surfaces 101 i and 101 ii are substantially unpassivated, and in some embodiments pristine.

Apparatus' 400A-D may be divided into two main sections or regions. First section 410 i (typically a staging section) is where the initial stock of lithium metal 430 (e.g., an ingot or foil of lithium) is positioned for entry or disposition into second section 410 ii (surface generating section), and, in particular, surface forming chamber 450 wherein lithium layer 101 and/or its pristine first surface 101 i (and optionally 101 i) are formed in direct contact with protective fluid 402 (e.g., super dry inert hydrocarbon liquid as described above). Chamber 450 includes enclosure 451, and is equipped with surface forming device 452, and interior environmental controls not shown. Once created, as-formed lithium layer 101 may be wound and/or stored in protective liquid of the same or different composition as that in which the layer itself (or at least its first surface) was generated. As shown in FIG. 4A, as formed lithium layer 101 is wound to form lithium roll 401-R. The winding may be performed inside chamber 450 (as shown), or lithium layer 101 may be fed to a separate downstream chamber for subsequent winding and storage in roll form.

In various embodiments, a lithium decal (as shown in FIG. 2D) may be formed by interleaving one or a pair of solid release layers (e.g., a polyolefin sheet or film) into the roll during winding. As described above, in a lithium decal of the present disclosure, the solid release layer is positioned on the first and/or second major surface where it keeps the inert liquid in place, ensures that the liquid spreads evenly over surface 101 i, mitigates evaporative losses because it (the solid release) enhances barrier properties, provides physical protection against contact damage, enables the use of protective liquids having relatively high vapor pressures, and serves as an interleave when stacking or rolling the layer(s) to avoid sticking. Once the decal is wound, surface 101 i is encapsulated by a protective liquid layer, and in some embodiments the liquid may be caused to form a sheath about the layer, which encapsulates both first and second surfaces.

With reference to FIGS. 4A-B and FIG. 4D, in various embodiments, both first and second major opposing surfaces (101 i and 101 ii; see figure inserts) are formed in direct contact with protective liquid by action of surface forming device 452 having surface forming component(s) 456 a/b that directly contact lithium metal layer 101 as it forms. As shown, surface forming device 452 may be a roller reduction mill that reduces thickness of the lithium metal layer and in so doing produces substantially unpassivated lithium surfaces by extruding initial stock 430, or lithium layer 405 (as shown in FIG. 4A), between rollers 456 a/b. When roller reducing a lithium metal foil, the area of the new surface created is proportional to the decrease in thickness.

Surface forming device 452 contacts protective liquid 402 such that as lithium metal layer 101 is formed, or surface 101 i and/or surface 101 i is created, the as-formed surfaces substantially instantaneously become immersed in protective fluid (e.g., inert liquid). Once the layer is formed, the inert liquid is caused to remain on the freshly created lithium layer surfaces (e.g., by using a solid release layer on that surface), typically fully encompassing (i.e., encapsulating) the surface, and thereon protecting it (the pristine surface) from direct contact with lithium reactive constituents that may be present as contaminants in of the ambient environment about the layer. In various embodiments, the protective fluid in which pristine lithium metal surface 101 a is formed may be exchanged with protective fluid having a different composition for downstream processing and/or storage. For instance, surface 101 i formed in or under a first protective liquid having a first vapor pressure or boiling point and that first inert liquid is replaced by a second inert liquid having a second vapor pressure or boiling point (e.g., the second liquid having a higher vapor pressure and lower boiling point than the first liquid, or vice-versa).

In various embodiments, surface forming device 452 is fully, or at least partially, immersed in protective fluid 402. For instance, active surface forming component 456, may be fully submerged or encompassed inside a bath of protective liquid. To contain protective liquid 102, surface generating section 410 ii includes enclosure 451 (e.g., an environmental chamber). In various embodiments, the surface forming device, and in particular its surface forming components, are also housed in the enclosure.

In various embodiments protective fluid 402 is a liquid at room temperature (i.e., 18° C. to 25° C.) and standard pressure (1 atm), and is primarily contained in the enclosure as a liquid. In various embodiments the interior environment of the enclosure is substantially filled by inert liquid, and as described above, and in more detail herein below, in various embodiments surface forming component 456 is immersed in the inert liquid phase protective fluid, and specifically that portion of the surface forming component which directly contacts lithium metal surface 101 i is immersed in the liquid phase. Accordingly, surface 101 i, or both surfaces 101 i and 101 bii, are formed in direct contact with liquid phase protective fluid, and preferably the as-formed surfaces are fully encompassed/encapsulated by the liquid phase, and as such the surfaces are formed in the absence of direct contact with a gaseous phase environment (e.g., dry air or an inert gas phase environment, including one or more noble gases), and thus also not formed in a vacuum environment. For instance, the lithium metal layer and/or its associated surfaces are fully formed immersed in a protective liquid. For example, formed inside a bath of protective liquid or inside a chamber filled with protective vapor of an inert liquid.

As described in more detail herein below, once formed within the protective liquid, lithium metal layer 101, or its first and/or second major surface(s) 101 i/101 ii are maintained in the protective liquid for subsequent winding to form a roll of lithium metal foil 101-R (typically on a spool) and/or storage. By this expedient, as-formed lithium metal layer 101, and/or surface 101 i, or both surfaces 101 i and 101 ii, have never been exposed to a gaseous phase environment or to a vacuum environment. In such embodiments, the lithium metal foil and its associated pristine surfaces, are formed, and thereafter stored in a pristine state, never exposed in direct contact with a gaseous atmosphere. For example, the foils so formed are maintained pristine during storage inside a bath of protective liquid for more than 24 hours, or more than 1 week, or more than 1 month. The pristine foils may then be sold and/or transported as such to a facility for manufacture of downstream battery cell components, including solid-state electrode laminates and battery cells of the present disclosure. In various embodiments the lithium foils are stored under protective liquid, and are preferably never been exposed in direct contact with gaseous atmospheres, including dry noble gases such as dry argon gas, or dry Helium gas, or some combination thereof, or even dry air (i.e., air having a very low moisture content, such as that typical of a dry room). When rolled with a solid release layer, the release removably covers and protects the substantially unpassivated lithium metal surface 101 i, and optionally its opposing surface 101 ii. When a solid release is used the inert liquid layer is formed and sandwiched between the solid release layer and the lithium metal layer, and this laminate structure is sometimes referred to herein as a wet-decal architecture, or more simply a wet-decal. Preferably, the inert liquid is capable of wetting out both the lithium metal surface and the release layer.

In alternative embodiments the interior environment of chamber 450 is primarily composed of protective fluid as a vapor. In such embodiments, the vapor molecules may condense on the as-formed lithium metal surfaces. When a vapor phase protective fluid is used, the enclosure is typically vacuum evacuated, followed by evaporating the protective liquid inside the chamber to form the inert vapor. Notably, when referring to vapor phase protective fluid it is not meant a noble gas such as argon or Helium, or the like. By protective fluid in the vapor phase it is meant vapor of the inert liquid.

With reference to FIG. 4A there is illustrated apparatus 400A for making pristine lithium metal layer 101 in protective fluid 402; for example, a super dry liquid hydrocarbon. With particular reference to FIG. 4A, initial lithium metal stock 430 (e.g., a lithium ingot) is extruded via die press 440 to form relatively thick freshly extruded lithium layer 405 (typically in the range of 75 to 500 um thick). Specifically, lithium ingot 430 is loaded and pressed against extrusion die 444 via plunger 442 and die plate 443, as is known in the art for making extruded lithium foil from lithium ingots in a gaseous dry room atmosphere.

As-formed, layer 405 is generally substantially unpassivated and preferably pristine upon exiting die 444. If formed in direct contact with a gaseous dry room environment the freshly made lithium metal surface would immediately start chemically reacting with the oxygen and carbon dioxide in the dry room, which would passivate the exposed surfaces. With respect to various embodiments of the present disclosure, because layer 405 is formed directly in protective liquid 102, its major opposing surfaces 105 a/105 b are fully covered in direct contact with protective liquid 102 substantially immediately upon formation (e.g. in less than one second). In the instant embodiment, thickness of layer 405 is reduced in a subsequent roll reduction step, as shown in section 410 ii of FIG. 4A. Once formed, layer 405 is caused (e.g., by a pulling tension) to enter roll reduction device 452, which can be a rolling mill having reduction work rolls 456 a/456 b, both of which are immersed in protective liquid inside enclosure 451. Work rolls 456 a-b may be made of compatible metal or plastic (e.g., polyacetal), or plastic coated metal rolls. Because the work rolls are immersed in protective hydrocarbon liquid, the issue of lithium metal sticking to the rolls is mitigated. In various embodiments roll reduction reduces the lithium layer down to a thickness of no greater than 50 um. Thin lithium metal layer 101 is formed upon exiting the roller mill; the roller reduction step effectively transforms pristine lithium layer 405 (e.g., 500 um thick) to thinner layer 101 having fresh surfaces 101 i and 101 ii formed in direct contact with protective liquid 402. Once formed layer 101 may be transferred from chamber 450 to a distinct/discrete winding chamber, or the winding device may be incorporated in chamber 450, and layer 101 subsequently wound to yield lithium foil roll 401-R, which, in its wound condition, remains directly exposed in contact with protective liquid (e.g., the protective liquid forming a thin layer of liquid between the lithium metal layer and a solid release layer, not shown). As described in more detail herein below, and with reference to a lithium roll package assembly of the present disclosure, wound roll 401-R may be stored in a functional canister containing protective liquid of the same or different composition as that of protective liquid 402, and a sealable port for ease of dispensing the lithium layer during battery cell or battery cell component manufacture. In various embodiments a solid release layer is positioned on the substantially unpassivated lithium surface (e.g., during winding or stacking), and the laminate structure so formed has, what is termed herein, a wet-decal architecture as described in more detail herein below.

Continuing with reference to FIGS. 4A-D, in various embodiments lithium metal layer 101 is a thin lithium metal layer, typically of thickness no greater than 50 μm, and more typically no greater than 25 μm (e.g., the thickness (t) of layer 101 is in the range of: 25 μm≥t>20 μm; or 20 μm≥t>15 μm; or 15 μm≥t>10 μm; or 10 μm≥t>5 μm). The standalone lithium metal layer may be self-supporting (if thicker than about 20 μm) or supported on a substrate layer. As described in more detail herein below, in various embodiments the lithium metal layer may be supported on a thin substrate layer that also serves as a current collector, the combination of current collector and thin lithium metal layer is sometimes referred to herein as having an electrode architecture.

As shown in FIG. 4B, in an alternative embodiment, initial lithium stock 430 may be a continuous foil of lithium (e.g. in the form of wound roll 430-R). As stock 430 is already in foil form, it may be contained inside a chamber that is configured for entry into chamber 450 via portal 455, or the layer may be exposed to the ambient external environment about chamber 450 (e.g., a dry box or dry room environment), and in this instance the stock layer would have passivated surfaces. In operation, stock foil 430 is unwound and caused, by pulling tension, to extrude through work rolls 456 a/b immersed in protective liquid 402. As described above, once foil 430 is extruded through roller reduction mill 452, it is wound in a similar fashion as described above, to form lithium roll 401-R immersed in protective liquid. In various embodiments stock lithium foil 130 may be pre-passivated (e.g., by exposing its surfaces to dry CO₂), and by this expedient improve reproducibility of the surface condition of the initial stock foil.

As shown in FIG. 4C, in yet another alternative embodiment stock foil 430 may be surface treated inside chamber 450 to expose a fresh lithium surface in direct contact with protective fluid 402 (e.g., ground with an abrasive element such as a brush or rough polymeric sheet). For instance, surface forming device 456 (e.g. an abrasive brush) may be positioned over stock foil 430 as it enters the chamber, and caused to engage with a surface of stock layer 430 to form pristine layer 101 and its associated pristine surface 101 i. In this embodiment the stock foil does not undergo a significant reduction in thickness, as the transformation of the foil from stock 430 to pristine layer 101 is based on forming pristine surface 101 i in direct contact with protective fluid 402 (e.g., liquid phase, vapor phase, or both). As shown in FIG. 4C, in various embodiments the stock may be a laminate of lithium layer 430 and a current collecting layer 461 in direct contact with the second surface of layer 430. In other embodiments, the stock is a lithium foil, and one or both surfaces are formed in the protective fluid, (e.g., by brushing/grinding).

With reference to FIG. 4D there is illustrated yet another alternative apparatus for making pristing lithium metal layer in the presence of protective fluid, and in accordance with the instant disclosure. The apparatus is similar to that described above for fresh surfaces produced by roll reduction, except in this embodiment the work rolls 456 a/b are positioned at the interface between the staging section 110 i and surface forming section 110 ii. Lithium stock foil 430 is configured for entry into the chamber via roller mill 455. In particular, work rolls 456 a/b effectively provide the portal into chamber 450, and the protective liquid is distributed to completely cover the freshly extruded surfaces (e.g., by spraying the inert liquid from nozzles 457 onto one or both surfaces 101 i/ii). Chamber 450 may be held under a dynamic vacuum with the protective fluid, in vapor form, or the chamber environment may be a combination of protective fluid in vapor form (i.e., protective vapor) and a dry noble gas such as argon or helium.

As described above, in various embodiments protective fluid 402 is a liquid. In some embodiments the interior environment of the chamber is held under a dynamic vacuum with protective fluid in the vapor phase. In some embodiments the protective fluid is present in the chamber in both the vapor and liquid phases. In some embodiments the chamber is substantially filled with liquid phase protective fluid (e.g., more than 90% of chamber volume is accounted for by protective liquid). Generally the protective fluid is a hydrocarbon composed of one or more hydrocarbon molecules that do not react in direct contact with lithium atoms.

With reference to FIG. 4E there is illustrated another embodiment in accordance with the instant disclosure for a process and apparatus 400E for fabricating pristine lithium metal layer 101 using a series of roller reduction mills (e.g., two or more). Apparatus 400E is generally disposed in a closed environmentally controlled chamber, similar or the same as chamber 451, as described above. Liquid phase protective fluid 402 is applied directly onto the major opposing surfaces of lithium stock 430 (e.g., by dripping or spraying), and is configured for extrusion rolling (i.e., roller reduction). Care should be taken to ensure that the major surfaces are entirely covered with protective liquid throughout the process. Additionally, protective liquid 402 is dispensed from fluid reservoir 432 for application directly onto work roll pairs 456 a/456 b and 456 c/456 d. A further application of the protective liquid is dispensed onto surface 101 i of the as-formed lithium metal layer 101 to ensure that the entirety of that surface is coated with a sufficient amount of protective liquid layer 102 to encapsulate the surfaces and provide sufficient protection for conveyance of the lithium foil 101 downstream for laminating processes, or for disposition into a canister for storage as a Li roll package assembly, as described below with reference to FIG. 6.

With reference to FIG. 4F there is illustrated top down views and cross sectional views qualitatively depicting the evolution of a lithium surface resulting from multiple roll reduction steps performed in protective liquid in accordance with various embodiments of the present disclosure. The initial lithium foil is stock and may be pre-passivated as shown (e.g. by treatment with carbon dioxide on its surface to form a lithium carbonate passivation layer). After the first roll reduction, the lithium thickness is reduced (as shown in the cross section depiction), and the lithium carbonate passivating layer has been broken apart to expose fresh lithium metal surfaces and scattered passivated islands. Because the steps are performed in protective liquid, and the lithium metal layer is maintained covered in protective liquid throughout the entire process, the freshly formed surfaces can remain unpassivated. With each consecutive roll reduction the thickness of the layer decreases and the area of the unpassivated surface region increases (also the passivated islands become smaller in size and area). As noted above, the decrease in lithium thickness is proportional to the increase in the unpassivated surface region. Accordingly, in various embodiments the method of making a thin lithium metal layer having a pristine surface includes: i) determining a final lithium metal layer thickness; determining the thickness of the stock of pre-passivated lithium metal layer necessary to create a pristine surface (i.e., at least 90% of the surface is defined by the unpassivated surface region); roll reduce the stock lithium metal foil under protective liquid. For instance, if the desired lithium metal thickness is 25 um, starting with a 50 um passivated lithium foil will produce a surface that is just 50% passivated and 50% unpassivated, which is insufficient for forming a pristine first major surface. To create a pristine lithium metal layer that is 25 um thick from pre-passivated lithium metal foil requires that the stock foil be at least 250 um thick.

With reference to FIG. 4G, stock lithium foil 430 may be simultaneously roller extruded and laminated to substrate layer 490 (e.g., a copper current collecting layer) using roller reduction mill 452 equipped with fluid dispensing reservoir 432 and work rolls 456 a/b as described above. Once processed, laminate structure 100B (as described with reference to FIG. 1B), has an electrode architecture that is composed of lithium metal layer 101 laminated with copper current collector 490F as the backing layer behind second major surface 101 ii. First major surface of layer 101 is entirely covered, in direct contact, with liquid phase protective fluid 102 (i.e., it is encapsulated). As-formed, laminate 100B may be subsequently wound and disposed into canister *** (as shown in FIG. 5) to form laminate roll package assembly for storage and ultimately downstream production of a lithium battery cell. In various embodiments the lithium metal layer may be roller extruded directly onto an inorganic solid electrolyte layer serving as substrate, such as a lithium ion conducting sulfide glass layer, the roll extrusion exposing substantially unpassivated lithium metal directly onto the sulfide glass to effect a reactive bond between the layers.

In accordance with the methods and apparatus' shown in FIGS. 4A-F, the process steps of: i) roller reducing the thickness of stock lithium metal foil; ii) forming freshly extruded lithium metal surfaces; iii) and laminating the second major surface 101 b to a copper current collector, may be performed in a conventional dry box or dry chamber having a noble gas atmosphere (e.g., argon or helium), with the interior environment of the dry box at low moisture content, preferably less than 10 ppm water, more preferably less than 5 ppm, even more preferably less than 1 ppm, and yet even more preferably less than 0.1 ppm. However, the embodiment is not limited to the apparatus being disposed in a conventional dry box, and in a manner similar to that shown in FIGS. 4A-D, apparatus' 400E/400F may be configured inside an environmentally controlled chamber, similar to that of chamber 450, with an interior atmosphere primarily composed of protective fluid (e.g., protective vapor).

With reference to FIGS. 5A-B there is illustrated a lithium metal roll assembly cartridge 500 (sometimes referred to herein as a lithium roll assembly package) in accordance with various embodiments of the present disclosure. Cartridge 500 includes Li decal laminate 100C in roll form 100C-Roll, and entirely immersed in protective inert liquid 502, which is itself contained in canister 571. The cartridge also includes sealable port 572 and associated sealing cap 573. FIG. 5A shows cartridge 500 in an hermetically closed state. FIG. 5B illustrates a mechanism for removing Li-decal laminate 100C from the canister, via sealable port 572, with sealing cap 573 configured to assist in dispensing the decal out of the canister. Cartridge 500 is suitable for storing the decal over extended time periods, including hours, days, or even weeks. The interior volume of canister 571 is substantially entirely filled with protective liquid, and may include moisture and oxygen gettering material, such as high surface area lithium metal in the form of numerable metal pieces immersed in the protective liquid.

Preferably cartridge 500 is sufficiently hermetic, and the protective liquid sufficiently dry (e.g., super dry), that lithium metal layer 101 is able to maintain its substantially unpassivated or pristine surface condition for at least 60 minutes, or at least 5 hours, or at least 10 hours, or at least 24 hours, or at least several days, weeks, or months (e.g., more than 3 days, more than 7 days, or more than 30 days).

Standalone Solid Electrolyte Laminate Structures

In accordance with the standalone electrochemical material laminate structure embodiments described with reference to FIGS. 2E-H, in various embodiments battery active material layer 201 is an inorganic alkali metal ion conducting solid electrolyte layer, and the laminate structure in such embodiments is referred to herein as an inorganic solid electrolyte laminate structure (e.g., a lithium ion conducting sulfide glass laminate structure). The room temperature alkali metal ion conductivity of the inorganic solid electrolyte layer is at least 10⁻⁶ S/cm, preferably at least 10⁻⁵ S/cm, and even more preferably at least 10⁻⁴ S/cm (e.g., between 10⁻⁵ S/cm and 10⁻⁴ S/cm or between 10⁻⁴ S/cm and 10⁻³ S/cm), with room temperature defined as 18° C.-25° C.

Continuing with reference to FIG. 2E-H in various embodiments inorganic alkali metal ion conductive solid electrolyte layer 201 is an inorganic lithium ion conductive solid electrolyte layer. In particular embodiments the inorganic lithium ion conductive solid electrolyte layer is an inorganic glass. In embodiments it is an oxide glass (in the absence of sulfur). In various embodiments inorganic solid electrolyte layer 201 is an lithium ion conductive sulfide glass. In various embodiments the inorganic solid electrolyte layer is moisture sensitive and chemically reacts in contact with water, and in particular the surface of the solid electrolyte layer degrades in the presence of the ambient atmosphere of a dry room (e.g., having a dew point at or below −20° C.) or that of a dry argon glove box (e.g., having between 0.1 to 10 ppm of water). In various embodiments, solid electrolyte layer 201 is a moisture sensitive Li ion conductive sulfide glass comprising lithium, sulfur and one or more of boron, silicon, and/or phosphorous. Particular sulfide solid electrolyte glasses that can benefit from incorporation into a solid electrolyte laminate structure of the present disclosure include those described in U.S. Patent Publication No.: 20160190640, which is hereby incorporated by reference for all that it contains; for example: 0.7Li₂S-0.29P₂S₅-0.01P₂O₅; 0.7Li₂S-0.28P₂S₅-0.02P₂O₅; 0.7Li₂S-0.27P₂S₅-0.03P₂O₅; 0.7Li₂S-0.26P₂S₅-0.04P₂O₅; 0.7Li₂S-0.25P₂S₅-0.05P₂O₅; 0.7Li₂S-0.24P₂S₅-0.06P₂O₅; 0.7Li₂S-0.23P₂S₅-0.07P₂O₅; 0.7Li₂S₅S-0.22P₂S₅-0.08P₂O₅; 0.7Li₂S-0.21P₂S₅-0.09P₂O₅; 0.7Li₂S-0.2P₂S₅-0.1P₂O₅; 0.7Li₂S-0.29B₂S₃-0.01B₂O₃; 0.7Li₂S-0.28B₂S₃-0.02B₂O₃; 0.7Li₂S-0.27B₂S₃-0.03B₂O₃; 0.7Li₂S-0.26B₂S₃-0.04B₂O₃; 0.7Li₂S-0.25B₂S₃-0.05B₂O₃; 0.7Li₂S-0.24B₂S₃-0.06B₂O₃; 0.7Li₂S-0.23B₂S₃-0.07B₂O₃; 0.7Li₂S-0.22B₂S₃-0.08B₂O₃; 0.7Li₂S-0.21B₂S₃-0.09B₂O₃; 0.7Li₂S-0.20B₂S₃-0.1B₂O₃; 0.7Li₂S-0.29B₂S₃-0.01P₂O₅; 0.7Li₂S-0.28B₂S₃-0.02P₂O₅; 0.7Li₂S-0.27B₂S₃-0.03P₂O₅; 0.7Li₂S-0.26B₂S₃-0.04P₂O₅; 0.7Li₂S-0.25B₂S₃-0.05P₂O₅; 0.7Li₂S-0.24B₂S₃-0.06P₂O₅; 0.7Li₂S-0.23B₂S₃-0.07P₂O₅; 0.7Li₂S-0.22B₂S₃-0.08P₂O₅; 0.7Li₂S- 0.21B₂S₃-0.09P₂O₅; 0.7Li₂S-0.20B₂S₃-0.1P₂O₅; 0.7Li₂S-0.29B₂S₃-0.01 SiS₂; 0.7Li₂S-0.28B₂S₃-0.02SiS₂; 0.7Li₂S-0.27B₂S₃-0.03SiS₂; 0.7Li₂S-0.26B₂S₃-0.04SiS₂; 0.7Li₂S-0.25B₂S₃-0.05SiS₂; 0.7Li2S-0.24B₂S₃-0.06SiS₂; 0.7Li₂S-0.23B₂S₃-0.07SiS₂; 0.7Li₂S-0.22B₂S₃-0.08SiS₂; 0.7Li₂S-0.21B₂S₃-0.09SiS₂; 0.7Li₂S-0.2B₂S₃-0.1SiS₂.

In other embodiments inorganic solid electrolyte layer 201 is a polycrystalline ceramic or a glass-ceramic layer (e.g., a garnet solid electrolyte layer). These include Li₆BaLa₂Ta₂O₁₂; Li₇La₃Zr₂O₁₂, Li₅La₃Nb₂O₁₂, Li₅La₃M₂O₁₂ (M=Nb, Ta)Li_(7+x)A_(x)La_(3−x)Zr₂O₁₂ where A may be Zn. These materials and methods for making them are described in U.S. Patent Application Pub. No.: 2007/0148533 (application Ser. No. 10/591,714) and is hereby incorporated by reference in its entirety and suitable garnet like structures, are described in International Patent Application Pub. No.: WO/2009/003695 which is hereby incorporated by reference for all that it contains. Suitable ceramic ion active metal ion conductors are described, for example, in U.S. Pat. No. 4,985,317 to Adachi et al., incorporated by reference herein in its entirety and for all purposes. LiM₂(PO₄)₃ where M may be Ti, Zr, Hf, Ge) and related compositions such as Li those into which certain ion substitutions are made including Li_(1+x)Ti_(2−x)Al_(x)(PO₄)₃ and the like which are known in the lithium battery arts.

Generally, the thickness of the inorganic sold electrolyte layer is in a range that is sensible for use in a battery cell, and generally depends, in part, on its ionic conductivity. In various embodiments the thickness of the solid electrolyte layer is in the range of 200-1 um thick, and more typically in the range of 100-5 μm, and even more typically in the range of 50-10 μm thick (e.g., about 10 μm or about 15 μm or about 20 μm or about 25 μm or about 30 μm or about 35 μm or about 40 μm or about 45 μm or about 50 μm thick).

Solid Electrolyte Interphase (Engineered SEI)

With reference to FIG. 6A, there is illustrated an apparatus 600 and method for cleaning a sulfide solid electrolyte glass layer and treating its surface to engineer a solid electrolyte interphase (SEI). The apparatus includes environmental chamber 650 having a very low moisture and oxygen content (e.g., less than 1 ppm), supply roll 605-R of sulfide glass sheet in roll form, web carrier for translating sheet 201 through cleaning chamber 620 and surface treatment chamber 630. Cleaning chamber 620 is a plasma treatment chamber for ion etching the glass under argon plasma. The ion-etching/plasma etching step removes products of sulfide glass hydrolysis by etching off a thin layer of glass from the surface, typically in the range of 0.5 to 10 nm. Once surface 201 i has been etched clean, it may be brought substantially immediately into cartridge 680 which is canister 681 filled with super dry hydrocarbon protective liquid 602, as described and listed above. Cartridge 680 receives the cleaned glass by rolling to form sulfide glass roll 610-R. Once immersed in the protective liquid, the cleaned surface can be preserved as such. Cartridge 680 is suitable for storing the decal over extended time periods, including hours, days, or even weeks. The interior volume of canister 571 is substantially entirely filled with protective liquid, and may include moisture and oxygen gettering material, such as high surface area lithium metal in the form of numerous metal pieces immersed in the protective liquid.

In various embodiments the sulfide glass surface 201 i is not chemically compatible in contact with lithium metal, and so coatings on the glass surface are described herein which are useful for creating a solid electrolyte interphase (SEI), the SEI forming as a result of the coating reacting with the substantially unpassivated lithium metal surface during the step of reactive bonding (e.g., during lamination of the layers, typically using heat and pressure).

In various embodiments, after ion etching, sulfide glass layer 201 is translated via the carrier web into surface treating chamber 630. In various embodiments surface treating chamber 630 is a second plasma unit, and glass 201 is subjected to nitrogen plasma and/or a nitrogen/argon plasma mixture, the process cleans the glass and also modifies the glass surface composition by introducing nitrogen into/onto the surface. Thereafter, the glass is wound into roll 610-R and immersed in protective liquid 602, as described above. In alternative embodiments, as opposed to bringing the cleaned and nitrogen treated glass into protective fluid (e.g., liquid or vapor phase), it is stored in a dry oxygen free argon filled enclosure.

Continuing with reference to FIG. 6A, in another embodiment, protective liquid 602 contains dissolved reactive species such as nitrogen and Halogens (e.g., iodine), which treats the glass surface as it (the glass layer) is immersed in protective hydrocarbon liquid. Additional reactive species such as nitrogen and Halogens may be injected into the canister as well. In yet another embodiment, the glass surface may be cleaned and surface treated in the same chamber. For example, inside chamber 620 the glass surface is cleaned with argon plasma, and then the argon gas in the chamber is displaced by protective fluid in the vapor phase containing sulfide glass reactive species such as nitrogen or Halogens (e.g., iodine 12 and iodine compounds).

In various embodiments the sulfide glass first major surface is treated in chamber 630 to form a thin precursor film that reacts with lithium metal to form an engineered solid electrolyte interphase (SEI). Various processes, reagents and treatments for engineering the SEI are described below.

With reference to FIG. 6B, in various embodiments a thin precursor film 640 may coated onto the clean first major surface of sulfide glass 201 to effect a solid electrolyte interphase via reaction with lithium metal during lamination, and preferably via reaction with pristine lithium metal surface.

In one embodiment precursor layer 640 is a halogen or interhalogen (diatomic or multi-atomic). For instance a monolayer, or several monolayers (e.g., up to 5 monolayers) of iodine or bromine molecules on the solid electrolyte glass surface is formed by condensation from the gas or liquid phase (e.g., gaseous or liquid phase iodine).

In one embodiment precursor layer is nitrogen. For example, a monolayer or several monolayers (e.g., up to 5 monolayers) of nitrogen molecules on the surface of the solid electrolyte gas is formed by condensation of nitrogen onto the solid electrolyte surface (from a gas or liquid phase). In a particular embodiment the nitrogen coated onto the surface of the solid electrolyte glass via a liquid carrier, such as liquid hydrocarbons, containing dissolved nitrogen molecules. The liquid hydrocarbons should be dry, as defined above, especially if the solid electrolyte is sensitive to moisture. Preferably the solubility of nitrogen in the hydrocarbon is large. For instance, the liquid carrier (e.g., liquid hydrocarbon) having a room temperature solubility of greater than 1 mole (nitrogen molecule) per mole of the liquid hydrocarbon, and preferably a ratio that is greater than 1.1, and even more preferably greater than 1.2. Particularly suitable liquid hydrocarbons include n-Octane, n-Nonane, n-Decane, n-Undecane, and n-Dodecane.

In other embodiments the solid electrolyte surface may be coated with a precursor of SO₂ or sulfur molecules, as described in more detail herein below.

While lithium is primarily referenced as the alkali metal layer material herein, it should be understood that other alkali metals or alloys of lithium may also be used.

Examples: Coatings on Glass Electrolyte Surface to Form SEI Via Reaction with Li

1. Halogens or Interhalogens (Diatomic or Multi-Atomic).

A monolayer, a few layers or condensed films are formed by iodine or bromine molecules on a glass surface from gas phase or from liquid phase. Halogen coating on the glass surface helps to improve wettability of Li metal towards glass (reactive wetting). In this case, the SEI formed on the clean Li surface consists of LiHal, in particular LiI or LiBr.

-   -   a. Halogen adsorption from the gas phase onto a glass surface at         elevated temperatures, room temperature, or low temperatures.

In order to minimize the coating thickness the source of iodine or bromine vapor is not a molecular halogen, but a halogen-containing compound having a lower halogen vapor pressure. The coating thickness can be optimized by using halogen-containing compounds with appropriate vapor pressure and by adjusting duration and temperature of the coating process. Among the compounds that are used as sources of halogen vapor are solid polyhalogens. Solid polyiodides with various cations described in (Per H. Svensson, Lars Kloo, Chemical Reviews, 2003, Vol. 103, No. 5) can be used as iodine sources (these compositions are incorporated by reference herein). Applicable polyhalogens include quaternary ammonium-polyhalogen compounds, in particular, tetraalkylammonium polyhalogens, inorganic polyiodides, such as RbI₃ CsI₃ and Cu—(NH₃)₄]I₄, charge transfer complexes between dioxane, pyridine, polyvinyl, pyrrolidone, polyethyleneoxide and halogens (as acceptors), such as poly(2vinylpyridine)iodine and poly(4-vinylpyridine)bromine complexes. Other examples include metal-halogen compounds, for instance, CuI.

-   -   b. Halogen coating of a glass surface from the liquid phase

The glass surface is coated with halogens by its treatment in solutions containing molecular halogens (iodine, bromine) or polyhalogens that are dissolved in dry (less than 1 ppm of moisture), non-polar solvents. In the preferred case, the solvents are selected from a group of unsaturated hydrocarbons or benzene and its homologues. In another case, the solvents are halogenated hydrocarbons, in particular, carbon tetrachloride. In another case, the solvent is carbon disulfide. The glass surface is brought into contact with or the glass is immersed into a solvent containing dissolved coating material (halogens or polyhalogens). Then the solvent is allowed to evaporate. In one case, Li—Mg or Li—Ca alloys (solid solution range) are used instead of Li metal. As a result, the SEI consists of LiI or LiBr doped with corresponding halides of Mg or Ca and has increased Li ion conductivity due to formation of Li cation vacancies (Schottky defects). In one case, both the glass surface and Li are treated in halogen vapor containing atmosphere. As a result, the halogen coating (preferentially, a very thin coating that consists of one or two molecular layers) is formed on the glass surface and a thin layer of LiHal is formed on the Li surface. After Li lamination onto glass, halogen molecules react with LiHal layer on Li forming an SEI consisting of a LiHal layer with increased thickness.

2. Nitrogen

A monolayer, a few layers or condensed films formed by nitrogen molecules on a glass surface from gas phase or from liquid phase at RT or low temperatures. At RT only one or two layers of nitrogen molecules are adsorbed onto metal surfaces, nitrogen can be adsorbed onto glass surfaces either in pure nitrogen atmosphere (the volume having been previously evacuated to high vacuum) or in a mixed nitrogen/inert gas atmosphere (Ar/N₂). In order to coat a long strip of glass, either a flow of pure nitrogen or a flow of carrier gas (Ar) mixed with nitrogen can be used.

In various embodiments, the resulting SEI is, or includes, Li₃N with a high Li ion conductivity.

In various embodiments the molecular nitrogen precursor layer is formed by coating the surface of the solid electrolyte glass sheet with a thin layer of a liquid hydrocarbon containing an amount of dissolved nitrogen molecules. In various embodiments the mole ratio of nitrogen molecules dissolved in the hydrocarbon carrier liquid is at least 0.05 moles of nitrogen molecules per mole of liquid hydrocarbon (N₂-moles/liq.hyd-moles). For instance, at least 0.1 N₂-moles/liq.hyd-moles, at least 0.2 N₂-moles/liq.hyd-moles, at least 0.3 N₂-moles/liq.hyd-moles, at least 0.4 N₂-moles/liq.hyd-moles, at least 0.5 N₂-moles/liq.hyd-moles, at least 1.0 N₂-moles/liq.hyd-moles. Particular suitable liquid hydrocarbon carriers are n-octane, n-nonane, n-decane, n-undecane, and n-dodecane.

When using a liquid carrier containing dissolved nitrogen molecules, the SEI formed when the nitrogen coated solid electrolyte layer is directly contacted with lithium metal is a lithium nitride compound (e.g., Li₃N), preferably fully reduced and highly conductive to lithium ions. As described above, the formation of the SEI may be effected during the lamination step, and the liquid hydrocarbons on the surface of the solid electrolyte layer and/or the lithium metal layer removed prior to and/or as a result of bond laminating the layers together.

3. SO₂

-   -   a. SO2 adsorption from the gas phase onto a glass surface at         elevated temperatures, RT or low temperatures. SO2 can be         adsorbed onto glass surfaces either in pure SO2 atmosphere (the         volume having been previously evacuated to high vacuum) or in a         mixed SO2/inert gas atmosphere (Ar/SO2).     -   b. SO2 coating of a glass surface at low temperature using         liquid SO2. In various embodiments, the resulting SEI is, or         includes, Li2S2O4, which is a known Li ion conductor.

4. Sulfur

-   -   a. Sublimation onto glass surface. S8 ring sulfur is known to be         the dominant sublimation phase.     -   b. Glass surface oxidation leading to formation of an elemental         S layer. In various embodiments, the resulting SEI is, or         includes, Li2S.         Solid-State Laminate Electrode Assembly

With reference to FIG. 7 there is illustrated standalone fully solid-state laminate electrode assembly 700 in accordance with various embodiments of the present disclosure. Laminate electrode assembly 700 is a laminate of alkali metal layer 101 having first major surface 101 i and ii) inorganic alkali metal ion conducting solid electrolyte layer 201 having first major surface 201 i. In various embodiments the alkali metal layer is a lithium metal layer and the inorganic solid electrolyte layer is an inorganic lithium ion conducting sulfide glass sheet, also as described above. In various embodiments, laminate 700 is formed by reactively bonding layer 101 (lithium metal) with layer 201 (sulfide glass) to form inorganic interface 705 (also referred to herein as the solid electrolyte interphase (SEI)) as ⅘ described in more detail herein below. The thickness of laminate 700 generally ranges from about 100 um down to as thin as about 5 um, and typically has a thickness in the range of 10 to 50 um. Preferably, the lithium ion resistance across the interface is less than 50 Ω-cm², and more preferably less than 25 Ω-cm².

The quality of inorganic interface 705 is a key aspect for determining how well the laminate electrode assembly will operate in a battery cell. Preferably, inorganic interface 705 is substantially uncontaminated by organic material, including organic residues of any inert liquid that may have been used in making, storing and processing of the laminate structures. In various embodiments the inorganic interface may be further characterized as “sufficiently uncontaminated by passivated alkali metal,” by which it is meant that at least 70% of the geometric area of the solid-state interface is uncontaminated by the presence of passivated alkali metal, such as patches of passivated alkali metal film (i.e., filmy patches), as well as pieces of passivated alkali metal that break off during battery cell cycling and/or handling, and could become trapped at the interface in the form of solid flakes, flecks or material bits of passivated alkali metal. Preferably, at least 80% of the geometric area of the solid-state interface is uncontaminated as such, and more preferably at least 90%, and even more preferably at least 95%, and yet even more preferably the entire geometric area of the solid-state interface is uncontaminated by the presence of passivated alkali metal flakes, flecks, filmy patches or material bits. To achieve an inorganic interface that is sufficiently uncontaminated by passivated alkali metal, surface 101 i of lithium metal layer 101 should be substantially unpassivated prior to bonding, and preferably the lithium metal layer surface is pristine. Additionally, the surface of the sulfide glass should be cleaned (e.g., by ion etching) immediately prior to bonding in order to remove solid products of sulfide glass hydrolysis.

When the reactive bond between the layers is continuous and complete, the laminate should exhibit exceptional adherence. In various embodiments the reactively bonded solid-state interface imparts exceptionally high peel strength to the standalone solid-state laminate electrode assembly (i.e., room temperature peel strength). For instance, the room temperature peel strength of the solid-state laminate electrode assembly is significantly greater than the tensile strength of the lithium metal layer to which it is bonded, such that during room temperature peel strength testing the lithium metal layer starts to deform, or tears, prior to peeling.

Methods of Making a Solid-State Laminate Electrode Assembly

With reference to FIG. 8 there is illustrated a process and apparatus 800 for making a fully solid-state laminate electrode assembly 700 in accordance with various embodiments of the present disclosure. The process takes place in an environmentally controlled chamber 850, and involves: i) providing a lithium metal laminate structure for processing into chamber 850, the laminate structure (as described above with reference to FIGS. 1A-D), the laminate structure composed of lithium metal layer 101 removably covered by protective inert liquid layer 102, which encapsulates first major surface 101 i, and second major surface 101 ii is held adjacent to current collector layer 103; providing for processing into chamber 850 an inorganic solid electrolyte laminate structure (as described above in various embodiments with reference to FIGS. 2A-D, the laminate composed of sulfide glass layer 201 having first major surface 201 i encapsulated by protective liquid layer 202. As shown in FIG. 8, sulfide glass layer is supported on its second major surface 102 ii by web carrier 805, which is not a component of the sulfide glass laminate structure. When the laminate structures include a solid release layer, it is removed on a take-up roll not shown. Both layers 101 and 201 enter chamber 830 for removing the inert liquid layer 102 and 202 respectively. Removal of the inert liquid layer can involve a series of steps which may be performed sequentially and/or in parallel. In various embodiments one or more of the following steps is taken to remove the inert liquid layer, including: applying heat to the layers (convectively and/or conductively), applying a vacuum suction over the respective layers, applying a jet of dry gas (Ar or He preferably) and/or a jet of a high vapor pressure hydrocarbon, replacing a low vapor pressure fluid with another higher pressure fluid, or some combination thereof.

Once the liquid layer has been removed from sulfide glass surface 201 i, the surface may be cleaned in ion etching chamber 820 using argon plasma (as described above with reference to chamber 620 in FIG. 6). The cleaned sulfide glass may then be transferred into surface treating station 850 where it may undergo a second plasma treatment with nitrogen or a mixture of nitrogen and argon, or it may be coated in chamber 850 to form a thin precursor film that is reactive with substantially unpassivated lithium metal to form a conductive solid electrolyte interphase. For instance, in various embodiments it may be coated with a thin layer of iodine or an iodine compound (e.g., condensing the iodine on the glass surface). Once the glass has been cleaned and/or its surface composition modified or coated with a thin precursor film, layers 101 and 201 are brought into laminating station 860 where they are reactive bonded to each other, generally by an application of both heat and pressure (via rollers 812) to form a fully solid-state laminate electrode assembly of the present disclosure.

Laminate electrode assembly 700, which may be formed as described above, includes second major surface 201 ii of the sulfide glass, and which may be highly sensitive to moisture. Accordingly, in various embodiments, after laminate electrode assembly 700 has been formed it may be stored in a sealed cartridge 900, as shown in FIG. 9. Cartridge 900 contains a bath of super dry hydrocarbon protective liquid 902 and laminate assembly 700 immersed in the bath, and in this way preserves the sulfide glass second major surface. Cartridge 900 is suitable for storing laminate electrode assembly 700 over extended time periods, including hours, days, or even weeks.

Battery Cells

With reference to FIG. 10 there is illustrated battery cell 1000 composed of fully solid-state laminate electrode assembly 700 combined with positive electrode 1030, such as a lithium ion intercalating material electrode (e.g., intercalating transition metal oxides), and battery electrolyte 1010, disposed between the second major surface of sulfide glass layer 201 and positive electrode 1010. In various embodiments it is contemplated that the battery cell is fully solid-state. In some fully solid-state battery embodiments, it is contemplated that the positive electrode is disposed in direct contact with the sulfide glass second major surface, in the absence of battery electrolyte layer 1010. In other embodiments, battery cell 1000 may be a liquid or gel electrolyte battery wherein electrolyte layer 1010 is a liquid electrolyte impregnated porous polymer membrane and/or a gel electrolyte layer. The method of making the battery cell may include providing the solid state laminate electrode assembly and disposing it in a battery cell housing adjacent to a liquid electrolyte impregnated in a Celgard-like porous polymer layer, and placing the positive electrode adjacent to it.

CONCLUSION

It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art. Although various details have been omitted for clarity's sake, various design alternatives may be implemented. Therefore, the present examples are to be considered as illustrative and not restrictive, and the disclosure is not to be limited to the details given herein, but may be modified within the scope of the appended claims. 

What is claimed:
 1. A method for making a battery cell, the method comprising making a solid-state electrode assembly comprising the steps of i) providing a lithium metal laminate structure, the lithium metal laminate structure comprising: a. a lithium metal layer having a first major surface that is substantially unpassivated; and b. a first fluid inert protective material layer that removably covers the lithium metal layer first major surface, the first inert protective material layer in direct contact with the lithium metal layer first major surface; ii) providing an inorganic solid electrolyte laminate structure, the electrolyte laminate structure comprising: a. an inorganic lithium ion conducting sulfide glass layer having a first major surface and an opposing second major surface; and b. a second fluid inert protective material layer that removably covers the sulfide glass layer first major surface, the second inert protective material layer in direct contact with the sulfide glass layer; iii) removing the first inert protective material layer from the lithium metal layer first major surface; iv) removing the second inert protective material layer from the sulfide glass layer first major surface; v) reactively bonding the sulfide glass layer with the lithium metal layer via their first major surfaces; and wherein the reactive bond provides an interface between the sulfide glass layer and the lithium metal layer defined by a continuous solid electrolyte interphase; and placing a positive electrode layer adjacent to the second major surface of the sulfide glass layer.
 2. The method of claim 1, wherein the second fluid inert protective material layer on the sulfide glass layer first major surface is a layer of a second dry hydrocarbon liquid, and the first fluid inert protective material layer on the substantially unpassivated lithium metal layer first major surface is a layer of a first dry hydrocarbon liquid.
 3. The method of claim 2, wherein the first dry hydrocarbon liquid on the lithium metal layer surface is removed substantially immediately prior to the reactive bonding.
 4. The method of claim 3, wherein the removal of the first hydrocarbon liquid is accelerated by the application of one or more of heat, vacuum suction, blowing a jet of dry Ar or He, and blowing a jet of high vapor pressure protective liquid followed by vacuum suction.
 5. The method of claim 4, further comprising cleaning the first major surface of the sulfide glass layer by ion etching under an argon plasma, wherein the cleaning is performed after the liquid phase layer of the second dry hydrocarbon liquid has been removed.
 6. The method of claim 3, wherein the first liquid phase protective fluid is a hydrocarbon liquid comprising not greater than 0.1 ppm of moisture.
 7. The method of claim 3, wherein the second dry hydrocarbon liquid on the sulfide glass layer is removed substantially immediately prior to the reactive bonding.
 8. The method of claim 7, wherein the second liquid phase protective fluid is a hydrocarbon liquid comprising not greater than 0.1 ppm of moisture. 